JUCE/modules/juce_audio_plugin_client/AU/juce_AUv3_Wrapper.mm

/*
  ==============================================================================

   This file is part of the JUCE 7 technical preview.
   Copyright (c) 2022 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For the technical preview this file cannot be licensed commercially.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

#include <juce_core/system/juce_TargetPlatform.h>
#include "../utility/juce_CheckSettingMacros.h"

#if JucePlugin_Build_AUv3

#if JUCE_MAC && ! (defined (MAC_OS_X_VERSION_10_11) && MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_11)
 #error AUv3 needs Deployment Target OS X 10.11 or higher to compile
#endif

#if (JUCE_IOS && defined (__IPHONE_15_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_15_0) \
   || (JUCE_MAC && defined (MAC_OS_VERSION_12_0) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_VERSION_12_0)
 #define JUCE_AUV3_MIDI_EVENT_LIST_SUPPORTED 1
#endif

#if (JUCE_IOS && defined (__IPHONE_11_0) && __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_11_0) \
   || (JUCE_MAC && defined (MAC_OS_X_VERSION_10_13) && MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_13)
 #define JUCE_AUV3_MIDI_OUTPUT_SUPPORTED 1
 #define JUCE_AUV3_VIEW_CONFIG_SUPPORTED 1
#endif

#ifndef __OBJC2__
 #error AUv3 needs Objective-C 2 support (compile with 64-bit)
#endif

#define JUCE_CORE_INCLUDE_OBJC_HELPERS 1

#include "../utility/juce_IncludeSystemHeaders.h"
#include "../utility/juce_IncludeModuleHeaders.h"

#import <CoreAudioKit/CoreAudioKit.h>
#import <AudioToolbox/AudioToolbox.h>
#import <AVFoundation/AVFoundation.h>

#include <juce_graphics/native/juce_mac_CoreGraphicsHelpers.h>
#include <juce_audio_basics/native/juce_mac_CoreAudioLayouts.h>
#include <juce_audio_basics/native/juce_mac_CoreAudioTimeConversions.h>
#include <juce_audio_processors/format_types/juce_LegacyAudioParameter.cpp>
#include <juce_audio_processors/format_types/juce_AU_Shared.h>

#if JUCE_AUV3_MIDI_EVENT_LIST_SUPPORTED
 #include <juce_audio_basics/midi/ump/juce_UMP.h>
#endif

#define JUCE_VIEWCONTROLLER_OBJC_NAME(x) JUCE_JOIN_MACRO (x, FactoryAUv3)

#if JUCE_IOS
 #define JUCE_IOS_MAC_VIEW  UIView
#else
 #define JUCE_IOS_MAC_VIEW  NSView
#endif

#define JUCE_AUDIOUNIT_OBJC_NAME(x) JUCE_JOIN_MACRO (x, AUv3)

#include <future>

JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wnullability-completeness")

using namespace juce;

struct AudioProcessorHolder  : public ReferenceCountedObject
{
    AudioProcessorHolder() {}
    AudioProcessorHolder (AudioProcessor* p) : processor (p) {}
    AudioProcessor& operator*() noexcept        { return *processor; }
    AudioProcessor* operator->() noexcept       { return processor.get(); }
    AudioProcessor* get() noexcept              { return processor.get(); }

    struct ViewConfig
    {
        double width;
        double height;
        bool hostHasMIDIController;
    };

    std::unique_ptr<ViewConfig> viewConfiguration;

    using Ptr = ReferenceCountedObjectPtr<AudioProcessorHolder>;

private:
    std::unique_ptr<AudioProcessor> processor;

    AudioProcessorHolder& operator= (AudioProcessor*) = delete;
    AudioProcessorHolder (AudioProcessorHolder&) = delete;
    AudioProcessorHolder& operator= (AudioProcessorHolder&) = delete;
};

//==============================================================================
class JuceAudioUnitv3Base
{
public:
    JuceAudioUnitv3Base (const AudioComponentDescription& descr,
                         AudioComponentInstantiationOptions options,
                         NSError** error)
        JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wobjc-method-access")
        : au ([audioUnitObjCClass.createInstance() initWithComponentDescription: descr
                                                                        options: options
                                                                          error: error
                                                                      juceClass: this])
        JUCE_END_IGNORE_WARNINGS_GCC_LIKE
    {}

    JuceAudioUnitv3Base (AUAudioUnit* audioUnit) : au (audioUnit)
    {
        jassert (MessageManager::getInstance()->isThisTheMessageThread());
        initialiseJuce_GUI();
    }

    virtual ~JuceAudioUnitv3Base() = default;

    //==============================================================================
    AUAudioUnit* getAudioUnit() noexcept                                   { return au; }

    //==============================================================================
    virtual void reset()                                                   = 0;

    //==============================================================================
    virtual AUAudioUnitPreset* getCurrentPreset()                          = 0;
    virtual void setCurrentPreset(AUAudioUnitPreset*)                      = 0;
    virtual NSArray<AUAudioUnitPreset*>* getFactoryPresets()               = 0;

    virtual NSDictionary<NSString*, id>* getFullState()
    {
        return ObjCMsgSendSuper<AUAudioUnit, NSDictionary<NSString*, id>*> (getAudioUnit(), @selector (fullState));
    }

    virtual void setFullState (NSDictionary<NSString*, id>* state)
    {
        ObjCMsgSendSuper<AUAudioUnit, void> (getAudioUnit(), @selector (setFullState:), state);
    }

    virtual AUParameterTree* getParameterTree()                            = 0;
    virtual NSArray<NSNumber*>* parametersForOverviewWithCount (int)       = 0;

    //==============================================================================
    virtual NSTimeInterval getLatency()                                    = 0;
    virtual NSTimeInterval getTailTime()                                   = 0;

    //==============================================================================
    virtual AUAudioUnitBusArray* getInputBusses()                          = 0;
    virtual AUAudioUnitBusArray* getOutputBusses()                         = 0;
    virtual NSArray<NSNumber*>* getChannelCapabilities()                   = 0;
    virtual bool shouldChangeToFormat (AVAudioFormat*, AUAudioUnitBus*)    = 0;

    //==============================================================================
    virtual int getVirtualMIDICableCount()                                 = 0;
    virtual bool getSupportsMPE()                                          = 0;
    virtual NSArray<NSString*>* getMIDIOutputNames()                       = 0;

    //==============================================================================
    virtual AUInternalRenderBlock getInternalRenderBlock()                 = 0;
    virtual bool getCanProcessInPlace()                                    { return false; }
    virtual bool getRenderingOffline()                                     = 0;
    virtual void setRenderingOffline (bool offline)                        = 0;

    virtual bool getShouldBypassEffect()
    {
        return (ObjCMsgSendSuper<AUAudioUnit, BOOL> (getAudioUnit(), @selector (shouldBypassEffect)) == YES);
    }

    virtual void setShouldBypassEffect (bool shouldBypass)
    {
        ObjCMsgSendSuper<AUAudioUnit, void> (getAudioUnit(), @selector (setShouldBypassEffect:), shouldBypass ? YES : NO);
    }

    //==============================================================================
    virtual NSString* getContextName()      const                          = 0;
    virtual void setContextName (NSString*)                                = 0;

    virtual bool allocateRenderResourcesAndReturnError (NSError **outError)
    {
        return (ObjCMsgSendSuper<AUAudioUnit, BOOL, NSError**> (getAudioUnit(), @selector (allocateRenderResourcesAndReturnError:), outError) == YES);
    }

    virtual void deallocateRenderResources()
    {
        ObjCMsgSendSuper<AUAudioUnit, void> (getAudioUnit(), @selector (deallocateRenderResources));
    }

    //==============================================================================
   #if JUCE_AUV3_VIEW_CONFIG_SUPPORTED
    JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wunguarded-availability", "-Wunguarded-availability-new")
    virtual NSIndexSet* getSupportedViewConfigurations (NSArray<AUAudioUnitViewConfiguration*>*) = 0;
    virtual void selectViewConfiguration (AUAudioUnitViewConfiguration*) = 0;
    JUCE_END_IGNORE_WARNINGS_GCC_LIKE
   #endif

private:
    struct Class  : public ObjCClass<AUAudioUnit>
    {
        Class() : ObjCClass<AUAudioUnit> ("AUAudioUnit_")
        {
            addIvar<JuceAudioUnitv3Base*> ("cppObject");

            JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wundeclared-selector")
            addMethod (@selector (initWithComponentDescription:options:error:juceClass:), initWithComponentDescriptionAndJuceClass);
            JUCE_END_IGNORE_WARNINGS_GCC_LIKE

            addMethod (@selector (initWithComponentDescription:options:error:), initWithComponentDescription);

            addMethod (@selector (dealloc),                         dealloc);

            //==============================================================================
            addMethod (@selector (reset),                           reset);

            //==============================================================================
            addMethod (@selector (currentPreset),                   getCurrentPreset);
            addMethod (@selector (setCurrentPreset:),               setCurrentPreset);
            addMethod (@selector (factoryPresets),                  getFactoryPresets);
            addMethod (@selector (fullState),                       getFullState);
            addMethod (@selector (setFullState:),                   setFullState);
            addMethod (@selector (parameterTree),                   getParameterTree);
            addMethod (@selector (parametersForOverviewWithCount:), parametersForOverviewWithCount);

            //==============================================================================
            addMethod (@selector (latency),                         getLatency);
            addMethod (@selector (tailTime),                        getTailTime);

            //==============================================================================
            addMethod (@selector (inputBusses),                     getInputBusses);
            addMethod (@selector (outputBusses),                    getOutputBusses);
            addMethod (@selector (channelCapabilities),             getChannelCapabilities);
            addMethod (@selector (shouldChangeToFormat:forBus:),    shouldChangeToFormat);

            //==============================================================================
            addMethod (@selector (virtualMIDICableCount),           getVirtualMIDICableCount);

            JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wundeclared-selector")
            addMethod (@selector (supportsMPE),                     getSupportsMPE);
            JUCE_END_IGNORE_WARNINGS_GCC_LIKE

           #if JUCE_AUV3_MIDI_OUTPUT_SUPPORTED
            if (@available (macOS 10.13, iOS 11.0, *))
                addMethod (@selector (MIDIOutputNames), getMIDIOutputNames);
           #endif

            //==============================================================================
            addMethod (@selector (internalRenderBlock),             getInternalRenderBlock);
            addMethod (@selector (canProcessInPlace),               getCanProcessInPlace);
            addMethod (@selector (isRenderingOffline),              getRenderingOffline);
            addMethod (@selector (setRenderingOffline:),            setRenderingOffline);
            addMethod (@selector (shouldBypassEffect),              getShouldBypassEffect);
            addMethod (@selector (setShouldBypassEffect:),          setShouldBypassEffect);
            addMethod (@selector (allocateRenderResourcesAndReturnError:),  allocateRenderResourcesAndReturnError);
            addMethod (@selector (deallocateRenderResources),       deallocateRenderResources);

            //==============================================================================
            addMethod (@selector (contextName),                     getContextName);
            addMethod (@selector (setContextName:),                 setContextName);

            //==============================================================================
           #if JUCE_AUV3_VIEW_CONFIG_SUPPORTED
            if (@available (macOS 10.13, iOS 11.0, *))
            {
                addMethod (@selector (supportedViewConfigurations:),    getSupportedViewConfigurations);
                addMethod (@selector (selectViewConfiguration:),        selectViewConfiguration);
            }
           #endif

            registerClass();
        }

        //==============================================================================
        static JuceAudioUnitv3Base* _this (id self)                     { return getIvar<JuceAudioUnitv3Base*> (self, "cppObject"); }
        static void setThis (id self, JuceAudioUnitv3Base* cpp)         { object_setInstanceVariable           (self, "cppObject", cpp); }

        //==============================================================================
        static id initWithComponentDescription (id _self, SEL, AudioComponentDescription descr, AudioComponentInstantiationOptions options, NSError** error)
        {
            AUAudioUnit* self = _self;

            self = ObjCMsgSendSuper<AUAudioUnit, AUAudioUnit*, AudioComponentDescription,
                                    AudioComponentInstantiationOptions, NSError**> (self, @selector (initWithComponentDescription:options:error:), descr, options, error);

            JuceAudioUnitv3Base* juceAU = JuceAudioUnitv3Base::create (self, descr, options, error);

            setThis (self, juceAU);
            return self;
        }

        static id initWithComponentDescriptionAndJuceClass (id _self, SEL, AudioComponentDescription descr, AudioComponentInstantiationOptions options, NSError** error, JuceAudioUnitv3Base* juceAU)
        {
            AUAudioUnit* self = _self;

            self = ObjCMsgSendSuper<AUAudioUnit, AUAudioUnit*, AudioComponentDescription,
                                    AudioComponentInstantiationOptions, NSError**> (self, @selector(initWithComponentDescription:options:error:), descr, options, error);


            setThis (self, juceAU);
            return self;
        }

        static void dealloc (id self, SEL)
        {
            if (! MessageManager::getInstance()->isThisTheMessageThread())
            {
                WaitableEvent deletionEvent;

                struct AUDeleter  : public CallbackMessage
                {
                    AUDeleter (id selfToDelete, WaitableEvent& event)
                        : parentSelf (selfToDelete), parentDeletionEvent (event)
                    {
                    }

                    void messageCallback() override
                    {
                        delete _this (parentSelf);
                        parentDeletionEvent.signal();
                    }

                    id parentSelf;
                    WaitableEvent& parentDeletionEvent;
                };

                (new AUDeleter (self, deletionEvent))->post();
                deletionEvent.wait (-1);
            }
            else
            {
                delete _this (self);
            }
        }

        //==============================================================================
        static void reset (id self, SEL)                                                            { _this (self)->reset(); }

        //==============================================================================
        static AUAudioUnitPreset* getCurrentPreset (id self, SEL)                                   { return _this (self)->getCurrentPreset(); }
        static void setCurrentPreset (id self, SEL, AUAudioUnitPreset* preset)                      { return _this (self)->setCurrentPreset (preset); }
        static NSArray<AUAudioUnitPreset*>* getFactoryPresets (id self, SEL)                        { return _this (self)->getFactoryPresets(); }
        static NSDictionary<NSString*, id>* getFullState (id self, SEL)                             { return _this (self)->getFullState(); }
        static void setFullState (id self, SEL, NSDictionary<NSString *, id>* state)                { return _this (self)->setFullState (state); }
        static AUParameterTree*     getParameterTree (id self, SEL)                                 { return _this (self)->getParameterTree(); }
        static NSArray<NSNumber*>* parametersForOverviewWithCount (id self, SEL, NSInteger count)   { return _this (self)->parametersForOverviewWithCount (static_cast<int> (count)); }

        //==============================================================================
        static NSTimeInterval getLatency (id self, SEL)                                             { return _this (self)->getLatency(); }
        static NSTimeInterval getTailTime (id self, SEL)                                            { return _this (self)->getTailTime(); }

        //==============================================================================
        static AUAudioUnitBusArray* getInputBusses   (id self, SEL)                                 { return _this (self)->getInputBusses(); }
        static AUAudioUnitBusArray* getOutputBusses  (id self, SEL)                                 { return _this (self)->getOutputBusses(); }
        static NSArray<NSNumber*>* getChannelCapabilities (id self, SEL)                            { return _this (self)->getChannelCapabilities(); }
        static BOOL shouldChangeToFormat (id self, SEL, AVAudioFormat* format, AUAudioUnitBus* bus) { return _this (self)->shouldChangeToFormat (format, bus) ? YES : NO; }

        //==============================================================================
        static NSInteger getVirtualMIDICableCount (id self, SEL)                                    { return _this (self)->getVirtualMIDICableCount(); }
        static BOOL getSupportsMPE (id self, SEL)                                                   { return _this (self)->getSupportsMPE() ? YES : NO; }
        static NSArray<NSString*>* getMIDIOutputNames (id self, SEL)                                { return _this (self)->getMIDIOutputNames(); }

        //==============================================================================
        static AUInternalRenderBlock getInternalRenderBlock (id self, SEL)                          { return _this (self)->getInternalRenderBlock();  }
        static BOOL getCanProcessInPlace (id self, SEL)                                             { return _this (self)->getCanProcessInPlace() ? YES : NO; }
        static BOOL getRenderingOffline (id self, SEL)                                              { return _this (self)->getRenderingOffline() ? YES : NO; }
        static void setRenderingOffline (id self, SEL, BOOL renderingOffline)                       { _this (self)->setRenderingOffline (renderingOffline); }
        static BOOL allocateRenderResourcesAndReturnError (id self, SEL, NSError** error)           { return _this (self)->allocateRenderResourcesAndReturnError (error) ? YES : NO; }
        static void deallocateRenderResources (id self, SEL)                                        { _this (self)->deallocateRenderResources(); }
        static BOOL getShouldBypassEffect (id self, SEL)                                            { return _this (self)->getShouldBypassEffect() ? YES : NO; }
        static void setShouldBypassEffect (id self, SEL, BOOL shouldBypass)                         { _this (self)->setShouldBypassEffect (shouldBypass); }

        //==============================================================================
        static NSString* getContextName (id self, SEL)                                              { return _this (self)->getContextName(); }
        static void setContextName (id self, SEL, NSString* str)                                    { return _this (self)->setContextName (str); }

        //==============================================================================
       #if JUCE_AUV3_VIEW_CONFIG_SUPPORTED
        JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wunguarded-availability", "-Wunguarded-availability-new")
        static NSIndexSet* getSupportedViewConfigurations (id self, SEL, NSArray<AUAudioUnitViewConfiguration*>* configs) { return _this (self)->getSupportedViewConfigurations (configs); }
        static void selectViewConfiguration (id self, SEL, AUAudioUnitViewConfiguration* config)                          { _this (self)->selectViewConfiguration (config); }
        JUCE_END_IGNORE_WARNINGS_GCC_LIKE
       #endif
    };

    static JuceAudioUnitv3Base* create (AUAudioUnit*, AudioComponentDescription, AudioComponentInstantiationOptions, NSError**);

    //==============================================================================
    static Class audioUnitObjCClass;

protected:
    AUAudioUnit* au;
};

//==============================================================================
JuceAudioUnitv3Base::Class JuceAudioUnitv3Base::audioUnitObjCClass;

//==============================================================================
//=========================== The actual AudioUnit =============================
//==============================================================================
class JuceAudioUnitv3  : public JuceAudioUnitv3Base,
                         public AudioProcessorListener,
                         public AudioPlayHead,
                         private AudioProcessorParameter::Listener
{
public:
    JuceAudioUnitv3 (const AudioProcessorHolder::Ptr& processor,
                     const AudioComponentDescription& descr,
                     AudioComponentInstantiationOptions options,
                     NSError** error)
        : JuceAudioUnitv3Base (descr, options, error),
          processorHolder (processor)
    {
        init();
    }

    JuceAudioUnitv3 (AUAudioUnit* audioUnit, AudioComponentDescription, AudioComponentInstantiationOptions, NSError**)
        : JuceAudioUnitv3Base (audioUnit),
          processorHolder (new AudioProcessorHolder (createPluginFilterOfType (AudioProcessor::wrapperType_AudioUnitv3)))
    {
        init();
    }

    ~JuceAudioUnitv3() override
    {
        auto& processor = getAudioProcessor();
        processor.removeListener (this);

        if (bypassParam != nullptr)
            bypassParam->removeListener (this);

        removeEditor (processor);

        if (editorObserverToken != nullptr)
        {
            [paramTree.get() removeParameterObserver: editorObserverToken];
            editorObserverToken = nullptr;
        }
    }

    //==============================================================================
    void init()
    {
        inParameterChangedCallback = false;

        AudioProcessor& processor = getAudioProcessor();
        const AUAudioFrameCount maxFrames = [getAudioUnit() maximumFramesToRender];

       #ifdef JucePlugin_PreferredChannelConfigurations
        short configs[][2] = {JucePlugin_PreferredChannelConfigurations};
        const int numConfigs = sizeof (configs) / sizeof (short[2]);

        jassert (numConfigs > 0 && (configs[0][0] > 0 || configs[0][1] > 0));
        processor.setPlayConfigDetails (configs[0][0], configs[0][1], kDefaultSampleRate, static_cast<int> (maxFrames));

        Array<AUChannelInfo> channelInfos;

        for (int i = 0; i < numConfigs; ++i)
        {
            AUChannelInfo channelInfo;

            channelInfo.inChannels  = configs[i][0];
            channelInfo.outChannels = configs[i][1];

            channelInfos.add (channelInfo);
        }
       #else
        Array<AUChannelInfo> channelInfos = AudioUnitHelpers::getAUChannelInfo (processor);
       #endif

        processor.setPlayHead (this);

        totalInChannels  = processor.getTotalNumInputChannels();
        totalOutChannels = processor.getTotalNumOutputChannels();

        {
            channelCapabilities.reset ([[NSMutableArray<NSNumber*> alloc] init]);

            for (int i = 0; i < channelInfos.size(); ++i)
            {
                AUChannelInfo& info = channelInfos.getReference (i);

                [channelCapabilities.get() addObject: [NSNumber numberWithInteger: info.inChannels]];
                [channelCapabilities.get() addObject: [NSNumber numberWithInteger: info.outChannels]];
            }
        }

        editorObserverToken = nullptr;
        internalRenderBlock = CreateObjCBlock (this, &JuceAudioUnitv3::renderCallback);

        processor.setRateAndBufferSizeDetails (kDefaultSampleRate, static_cast<int> (maxFrames));
        processor.prepareToPlay (kDefaultSampleRate, static_cast<int> (maxFrames));
        processor.addListener (this);

        addParameters();
        addPresets();

        addAudioUnitBusses (true);
        addAudioUnitBusses (false);
    }

    AudioProcessor& getAudioProcessor() const noexcept        { return **processorHolder; }

    //==============================================================================
    void reset() override
    {
        midiMessages.clear();
        lastTimeStamp.mSampleTime = std::numeric_limits<Float64>::max();
    }

    //==============================================================================
    AUAudioUnitPreset* getCurrentPreset() override
    {
        const int n = static_cast<int> ([factoryPresets.get() count]);
        const int idx = static_cast<int> (getAudioProcessor().getCurrentProgram());

        if (idx < n)
            return [factoryPresets.get() objectAtIndex:static_cast<unsigned int> (idx)];

        return nullptr;
    }

    void setCurrentPreset (AUAudioUnitPreset* preset) override
    {
        const int n = static_cast<int> ([factoryPresets.get() count]);
        const int idx = static_cast<int> ([preset number]);

        if (isPositiveAndBelow (idx, n))
            getAudioProcessor().setCurrentProgram (idx);
    }

    NSArray<AUAudioUnitPreset*>* getFactoryPresets() override
    {
        return factoryPresets.get();
    }

    NSDictionary<NSString*, id>* getFullState() override
    {
        NSMutableDictionary<NSString*, id>* retval = [[NSMutableDictionary<NSString*, id> alloc] init];

        {
            NSDictionary<NSString*, id>* superRetval = JuceAudioUnitv3Base::getFullState();

            if (superRetval != nullptr)
                [retval addEntriesFromDictionary:superRetval];
        }

        juce::MemoryBlock state;

       #if JUCE_AU_WRAPPERS_SAVE_PROGRAM_STATES
        getAudioProcessor().getCurrentProgramStateInformation (state);
       #else
        getAudioProcessor().getStateInformation (state);
       #endif

        if (state.getSize() > 0)
        {
            NSData* ourState = [[NSData alloc] initWithBytes: state.getData()
                                                      length: state.getSize()];

            NSString* nsKey = [[NSString alloc] initWithUTF8String: JUCE_STATE_DICTIONARY_KEY];

            [retval setObject: ourState
                       forKey: nsKey];

            [nsKey    release];
            [ourState release];
        }

        return [retval autorelease];
    }

    void setFullState (NSDictionary<NSString*, id>* state) override
    {
        if (state == nullptr)
            return;

        NSMutableDictionary<NSString*, id>* modifiedState = [[NSMutableDictionary<NSString*, id> alloc] init];
        [modifiedState addEntriesFromDictionary: state];

        NSString* nsPresetKey = [[NSString alloc] initWithUTF8String: kAUPresetDataKey];
        [modifiedState removeObjectForKey: nsPresetKey];
        [nsPresetKey release];

        JuceAudioUnitv3Base::setFullState (modifiedState);

        NSString* nsKey = [[NSString alloc] initWithUTF8String: JUCE_STATE_DICTIONARY_KEY];
        NSObject* obj = [modifiedState objectForKey: nsKey];
        [nsKey release];

        if (obj != nullptr)
        {
            if ([obj isKindOfClass:[NSData class]])
            {
                NSData* data = reinterpret_cast<NSData*> (obj);
                const int numBytes = static_cast<int> ([data length]);
                const juce::uint8* const rawBytes = reinterpret_cast< const juce::uint8* const> ([data bytes]);

                if (numBytes > 0)
                {
                   #if JUCE_AU_WRAPPERS_SAVE_PROGRAM_STATES
                    getAudioProcessor().setCurrentProgramStateInformation (rawBytes, numBytes);
                   #else
                    getAudioProcessor().setStateInformation (rawBytes, numBytes);
                   #endif
                }
            }
        }

        [modifiedState release];
    }

    AUParameterTree* getParameterTree() override
    {
        return paramTree.get();
    }

    NSArray<NSNumber*>* parametersForOverviewWithCount (int count) override
    {
        const int n = static_cast<int> ([overviewParams.get() count]);

        if (count >= n)
            return overviewParams.get();

        NSMutableArray<NSNumber*>* retval = [[NSMutableArray<NSNumber*>alloc] initWithArray: overviewParams.get()];
        [retval removeObjectsInRange: NSMakeRange (static_cast<unsigned int> (count), static_cast<unsigned int> (n - count))];

        return [retval autorelease];
    }

    //==============================================================================
    NSTimeInterval getLatency() override
    {
        auto& p = getAudioProcessor();
        return p.getLatencySamples() / p.getSampleRate();
    }

    NSTimeInterval getTailTime() override
    {
        return getAudioProcessor().getTailLengthSeconds();
    }

    //==============================================================================
    AUAudioUnitBusArray* getInputBusses() override            { return inputBusses.get();  }
    AUAudioUnitBusArray* getOutputBusses() override           { return outputBusses.get(); }
    NSArray<NSNumber*>* getChannelCapabilities() override     { return channelCapabilities.get(); }

    bool shouldChangeToFormat (AVAudioFormat* format, AUAudioUnitBus* auBus) override
    {
        const bool isInput = ([auBus busType] == AUAudioUnitBusTypeInput);
        const int busIdx = static_cast<int> ([auBus index]);
        const int newNumChannels = static_cast<int> ([format channelCount]);

        AudioProcessor& processor = getAudioProcessor();

        if (AudioProcessor::Bus* bus = processor.getBus (isInput, busIdx))
        {
          #ifdef JucePlugin_PreferredChannelConfigurations
            ignoreUnused (bus);

            short configs[][2] = {JucePlugin_PreferredChannelConfigurations};

            if (! AudioUnitHelpers::isLayoutSupported (processor, isInput, busIdx, newNumChannels, configs))
                return false;
          #else
            const AVAudioChannelLayout* layout    = [format channelLayout];
            const AudioChannelLayoutTag layoutTag = (layout != nullptr ? [layout layoutTag] : 0);

            if (layoutTag != 0)
            {
                AudioChannelSet newLayout = CoreAudioLayouts::fromCoreAudio (layoutTag);

                if (newLayout.size() != newNumChannels)
                    return false;

                if (! bus->isLayoutSupported (newLayout))
                    return false;
            }
            else
            {
                if (! bus->isNumberOfChannelsSupported (newNumChannels))
                    return false;
            }
           #endif

            return true;
        }

        return false;
    }

    //==============================================================================
    int getVirtualMIDICableCount() override
    {
       #if JucePlugin_WantsMidiInput
        return 1;
       #else
        return 0;
       #endif
    }

    bool getSupportsMPE() override
    {
        return getAudioProcessor().supportsMPE();
    }

    NSArray<NSString*>* getMIDIOutputNames() override
    {
       #if JucePlugin_ProducesMidiOutput
        return @[@"MIDI Out"];
       #else
        return @[];
       #endif
    }

    //==============================================================================
    AUInternalRenderBlock getInternalRenderBlock() override   { return internalRenderBlock;  }
    bool getRenderingOffline() override                       { return getAudioProcessor().isNonRealtime(); }
    void setRenderingOffline (bool offline) override
    {
        auto& processor = getAudioProcessor();
        auto isCurrentlyNonRealtime = processor.isNonRealtime();

        if (isCurrentlyNonRealtime != offline)
        {
            ScopedLock callbackLock (processor.getCallbackLock());

            processor.setNonRealtime (offline);
            processor.prepareToPlay (processor.getSampleRate(), processor.getBlockSize());
        }
    }

    bool getShouldBypassEffect() override
    {
        if (bypassParam != nullptr)
            return (bypassParam->getValue() != 0.0f);

        return JuceAudioUnitv3Base::getShouldBypassEffect();
    }

    void setShouldBypassEffect (bool shouldBypass) override
    {
        if (bypassParam != nullptr)
            bypassParam->setValue (shouldBypass ? 1.0f : 0.0f);

        JuceAudioUnitv3Base::setShouldBypassEffect (shouldBypass);
    }

    //==============================================================================
    NSString* getContextName() const    override              { return juceStringToNS (contextName); }
    void setContextName (NSString* str) override
    {
        if (str != nullptr)
        {
            AudioProcessor::TrackProperties props;
            props.name = nsStringToJuce (str);

            getAudioProcessor().updateTrackProperties (props);
        }
    }

    //==============================================================================
    bool allocateRenderResourcesAndReturnError (NSError **outError) override
    {
        AudioProcessor& processor = getAudioProcessor();
        const AUAudioFrameCount maxFrames = [getAudioUnit() maximumFramesToRender];

        if (! JuceAudioUnitv3Base::allocateRenderResourcesAndReturnError (outError))
            return false;

        if (outError != nullptr)
            *outError = nullptr;

        AudioProcessor::BusesLayout layouts;
        for (int dir = 0; dir < 2; ++dir)
        {
            const bool isInput = (dir == 0);
            const int n = AudioUnitHelpers::getBusCountForWrapper (processor, isInput);
            Array<AudioChannelSet>& channelSets = (isInput ? layouts.inputBuses : layouts.outputBuses);

            AUAudioUnitBusArray* auBuses = (isInput ? [getAudioUnit() inputBusses] : [getAudioUnit() outputBusses]);
            jassert ([auBuses count] == static_cast<NSUInteger> (n));

            for (int busIdx = 0; busIdx < n; ++busIdx)
            {
                if (AudioProcessor::Bus* bus = processor.getBus (isInput, busIdx))
                {
                    AVAudioFormat* format = [[auBuses objectAtIndexedSubscript:static_cast<NSUInteger> (busIdx)] format];

                    AudioChannelSet newLayout;
                    const AVAudioChannelLayout* layout    = [format channelLayout];
                    const AudioChannelLayoutTag layoutTag = (layout != nullptr ? [layout layoutTag] : 0);

                    if (layoutTag != 0)
                        newLayout = CoreAudioLayouts::fromCoreAudio (layoutTag);
                    else
                        newLayout = bus->supportedLayoutWithChannels (static_cast<int> ([format channelCount]));

                    if (newLayout.isDisabled())
                        return false;

                    channelSets.add (newLayout);
                }
            }
        }

       #ifdef JucePlugin_PreferredChannelConfigurations
        short configs[][2] = {JucePlugin_PreferredChannelConfigurations};

        if (! AudioProcessor::containsLayout (layouts, configs))
        {
            if (outError != nullptr)
                *outError = [NSError errorWithDomain:NSOSStatusErrorDomain code:kAudioUnitErr_FormatNotSupported userInfo:nullptr];

            return false;
        }
       #endif

        if (! AudioUnitHelpers::setBusesLayout (&getAudioProcessor(), layouts))
        {
            if (outError != nullptr)
                *outError = [NSError errorWithDomain:NSOSStatusErrorDomain code:kAudioUnitErr_FormatNotSupported userInfo:nullptr];

            return false;
        }

        totalInChannels  = processor.getTotalNumInputChannels();
        totalOutChannels = processor.getTotalNumOutputChannels();

        allocateBusBuffer (true);
        allocateBusBuffer (false);

        mapper.alloc (processor);

        audioBuffer.prepare (AudioUnitHelpers::getBusesLayout (&processor), static_cast<int> (maxFrames));

        auto sampleRate = [&]
        {
            for (auto* buffer : { inputBusses.get(), outputBusses.get() })
                if ([buffer count] > 0)
                    return [[[buffer objectAtIndexedSubscript: 0] format] sampleRate];

            return 44100.0;
        }();

        processor.setRateAndBufferSizeDetails (sampleRate, static_cast<int> (maxFrames));
        processor.prepareToPlay (sampleRate, static_cast<int> (maxFrames));

        midiMessages.ensureSize (2048);
        midiMessages.clear();

        zeromem (&lastAudioHead, sizeof (lastAudioHead));
        hostMusicalContextCallback = [getAudioUnit() musicalContextBlock];
        hostTransportStateCallback = [getAudioUnit() transportStateBlock];

        if (@available (macOS 10.13, iOS 11.0, *))
            midiOutputEventBlock = [au MIDIOutputEventBlock];

        reset();

        return true;
    }

    void deallocateRenderResources() override
    {
        midiOutputEventBlock = nullptr;

        hostMusicalContextCallback = nullptr;
        hostTransportStateCallback = nullptr;

        getAudioProcessor().releaseResources();
        audioBuffer.release();

        inBusBuffers. clear();
        outBusBuffers.clear();

        mapper.release();

        JuceAudioUnitv3Base::deallocateRenderResources();
    }

    //==============================================================================
   #if JUCE_AUV3_VIEW_CONFIG_SUPPORTED
    JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wunguarded-availability", "-Wunguarded-availability-new")
    NSIndexSet* getSupportedViewConfigurations (NSArray<AUAudioUnitViewConfiguration*>* configs) override
    {
        auto supportedViewIndecies = [[NSMutableIndexSet alloc] init];
        auto n = [configs count];

        if (auto* editor = getAudioProcessor().createEditorIfNeeded())
        {
            // If you hit this assertion then your plug-in's editor is reporting that it doesn't support
            // any host MIDI controller configurations!
            jassert (editor->supportsHostMIDIControllerPresence (true) || editor->supportsHostMIDIControllerPresence (false));

            for (auto i = 0u; i < n; ++i)
            {
                if (auto viewConfiguration = [configs objectAtIndex: i])
                {
                    if (editor->supportsHostMIDIControllerPresence ([viewConfiguration hostHasController] == YES))
                    {
                        auto* constrainer = editor->getConstrainer();
                        auto height = (int) [viewConfiguration height];
                        auto width  = (int) [viewConfiguration width];

                        if (height <= constrainer->getMaximumHeight() && height >= constrainer->getMinimumHeight()
                         && width  <= constrainer->getMaximumWidth()  && width  >= constrainer->getMinimumWidth())
                            [supportedViewIndecies addIndex: i];
                    }
                }
            }
        }

        return [supportedViewIndecies autorelease];
    }

    void selectViewConfiguration (AUAudioUnitViewConfiguration* config) override
    {
        processorHolder->viewConfiguration.reset (new AudioProcessorHolder::ViewConfig { [config width], [config height], [config hostHasController] == YES });
    }
    JUCE_END_IGNORE_WARNINGS_GCC_LIKE
   #endif

    struct ScopedKeyChange
    {
        ScopedKeyChange (AUAudioUnit* a, NSString* k)
            : au (a), key (k)
        {
            [au willChangeValueForKey: key];
        }

        ~ScopedKeyChange()
        {
            [au didChangeValueForKey: key];
        }

        AUAudioUnit* au;
        NSString* key;
    };

    //==============================================================================
    void audioProcessorChanged (AudioProcessor* processor, const ChangeDetails& details) override
    {
        ignoreUnused (processor);

        if (! details.programChanged)
            return;

        {
            ScopedKeyChange scope (au, @"allParameterValues");
            addPresets();
        }

        {
            ScopedKeyChange scope (au, @"currentPreset");
        }
    }

    void sendParameterEvent (int idx, const float* newValue, AUParameterAutomationEventType type)
    {
        if (inParameterChangedCallback.get())
        {
            inParameterChangedCallback = false;
            return;
        }

        if (auto* juceParam = juceParameters.getParamForIndex (idx))
        {
            if (auto* param = [paramTree.get() parameterWithAddress: getAUParameterAddressForIndex (idx)])
            {
                const auto value = (newValue != nullptr ? *newValue : juceParam->getValue()) * getMaximumParameterValue (juceParam);

                if (@available (macOS 10.12, iOS 10.0, *))
                {
                    [param setValue: value
                         originator: editorObserverToken
                         atHostTime: lastTimeStamp.mHostTime
                          eventType: type];
                }
                else if (type == AUParameterAutomationEventTypeValue)
                {
                    [param setValue: value originator: editorObserverToken];
                }
            }
        }
    }

    void audioProcessorParameterChanged (AudioProcessor*, int idx, float newValue) override
    {
        sendParameterEvent (idx, &newValue, AUParameterAutomationEventTypeValue);
    }

    void audioProcessorParameterChangeGestureBegin (AudioProcessor*, int idx) override
    {
        sendParameterEvent (idx, nullptr, AUParameterAutomationEventTypeTouch);
    }

    void audioProcessorParameterChangeGestureEnd (AudioProcessor*, int idx) override
    {
        sendParameterEvent (idx, nullptr, AUParameterAutomationEventTypeRelease);
    }

    //==============================================================================
    bool getCurrentPosition (CurrentPositionInfo& info) override
    {
        bool musicContextCallSucceeded = false;
        bool transportStateCallSucceeded = false;

        info = lastAudioHead;
        info.timeInSamples = (int64) (lastTimeStamp.mSampleTime + 0.5);
        info.timeInSeconds = info.timeInSamples / getAudioProcessor().getSampleRate();

        info.frameRate = [this]
        {
            switch (lastTimeStamp.mSMPTETime.mType)
            {
                case kSMPTETimeType2398:        return FrameRate().withBaseRate (24).withPullDown();
                case kSMPTETimeType24:          return FrameRate().withBaseRate (24);
                case kSMPTETimeType25:          return FrameRate().withBaseRate (25);
                case kSMPTETimeType30Drop:      return FrameRate().withBaseRate (30).withDrop();
                case kSMPTETimeType30:          return FrameRate().withBaseRate (30);
                case kSMPTETimeType2997:        return FrameRate().withBaseRate (30).withPullDown();
                case kSMPTETimeType2997Drop:    return FrameRate().withBaseRate (30).withPullDown().withDrop();
                case kSMPTETimeType60:          return FrameRate().withBaseRate (60);
                case kSMPTETimeType60Drop:      return FrameRate().withBaseRate (60).withDrop();
                case kSMPTETimeType5994:        return FrameRate().withBaseRate (60).withPullDown();
                case kSMPTETimeType5994Drop:    return FrameRate().withBaseRate (60).withPullDown().withDrop();
                case kSMPTETimeType50:          return FrameRate().withBaseRate (50);
                default:                        break;
            }

            return FrameRate();
        }();

        double num;
        NSInteger den;
        NSInteger outDeltaSampleOffsetToNextBeat;
        double outCurrentMeasureDownBeat, bpm;
        double ppqPosition;

        if (hostMusicalContextCallback != nullptr)
        {
            AUHostMusicalContextBlock musicalContextCallback = hostMusicalContextCallback;

            if (musicalContextCallback (&bpm, &num, &den, &ppqPosition, &outDeltaSampleOffsetToNextBeat, &outCurrentMeasureDownBeat))
            {
                musicContextCallSucceeded = true;

                info.timeSigNumerator   = (int) num;
                info.timeSigDenominator = (int) den;
                info.ppqPositionOfLastBarStart = outCurrentMeasureDownBeat;
                info.bpm = bpm;
                info.ppqPosition = ppqPosition;
            }
        }

        double outCurrentSampleInTimeLine, outCycleStartBeat = 0, outCycleEndBeat = 0;
        AUHostTransportStateFlags flags;

        if (hostTransportStateCallback != nullptr)
        {
            AUHostTransportStateBlock transportStateCallback = hostTransportStateCallback;

            if (transportStateCallback (&flags, &outCurrentSampleInTimeLine, &outCycleStartBeat, &outCycleEndBeat))
            {
                transportStateCallSucceeded = true;

                info.timeInSamples  = (int64) (outCurrentSampleInTimeLine + 0.5);
                info.timeInSeconds  = info.timeInSamples / getAudioProcessor().getSampleRate();
                info.isPlaying      = ((flags & AUHostTransportStateMoving) != 0);
                info.isLooping      = ((flags & AUHostTransportStateCycling) != 0);
                info.isRecording    = ((flags & AUHostTransportStateRecording) != 0);
                info.ppqLoopStart   = outCycleStartBeat;
                info.ppqLoopEnd     = outCycleEndBeat;
            }
        }

        if (musicContextCallSucceeded && transportStateCallSucceeded)
            lastAudioHead = info;

        return true;
    }

    //==============================================================================
    static void removeEditor (AudioProcessor& processor)
    {
        ScopedLock editorLock (processor.getCallbackLock());

        if (AudioProcessorEditor* editor = processor.getActiveEditor())
        {
            processor.editorBeingDeleted (editor);
            delete editor;
        }
    }

private:
    //==============================================================================
    struct BusBuffer
    {
        BusBuffer (AUAudioUnitBus* bus, int maxFramesPerBuffer)
            : auBus (bus),
              maxFrames (maxFramesPerBuffer),
              numberOfChannels (static_cast<int> ([[auBus format] channelCount])),
              isInterleaved ([[auBus format] isInterleaved])
        {
            alloc();
        }

        //==============================================================================
        void alloc()
        {
            const int numBuffers = isInterleaved ? 1 : numberOfChannels;
            int bytes = static_cast<int> (sizeof (AudioBufferList))
                          + ((numBuffers - 1) * static_cast<int> (sizeof (::AudioBuffer)));
            jassert (bytes > 0);

            bufferListStorage.calloc (static_cast<size_t> (bytes));
            bufferList = reinterpret_cast<AudioBufferList*> (bufferListStorage.getData());

            const int bufferChannels = isInterleaved ? numberOfChannels : 1;
            scratchBuffer.setSize (numBuffers, bufferChannels * maxFrames);
        }

        void dealloc()
        {
            bufferList = nullptr;
            bufferListStorage.free();
            scratchBuffer.setSize (0, 0);
        }

        //==============================================================================
        int numChannels() const noexcept                { return numberOfChannels; }
        bool interleaved() const noexcept               { return isInterleaved; }
        AudioBufferList* get() const noexcept           { return bufferList; }

        //==============================================================================
        void prepare (UInt32 nFrames, const AudioBufferList* other = nullptr) noexcept
        {
            const int numBuffers = isInterleaved ? 1 : numberOfChannels;
            const bool isCompatible = isCompatibleWith (other);

            bufferList->mNumberBuffers = static_cast<UInt32> (numBuffers);

            for (int i = 0; i < numBuffers; ++i)
            {
                const UInt32 bufferChannels = static_cast<UInt32> (isInterleaved ? numberOfChannels : 1);
                bufferList->mBuffers[i].mNumberChannels = bufferChannels;
                bufferList->mBuffers[i].mData = (isCompatible ? other->mBuffers[i].mData
                                                              : scratchBuffer.getWritePointer (i));
                bufferList->mBuffers[i].mDataByteSize = nFrames * bufferChannels * sizeof (float);
            }
        }

        //==============================================================================
        bool isCompatibleWith (const AudioBufferList* other) const noexcept
        {
            if (other == nullptr)
                return false;

            if (other->mNumberBuffers > 0)
            {
                const bool otherInterleaved = AudioUnitHelpers::isAudioBufferInterleaved (*other);
                const int otherChannels = static_cast<int> (otherInterleaved ? other->mBuffers[0].mNumberChannels
                                                                             : other->mNumberBuffers);

                return otherInterleaved == isInterleaved
                    && numberOfChannels == otherChannels;
            }

            return numberOfChannels == 0;
        }

    private:
        AUAudioUnitBus* auBus;
        HeapBlock<char> bufferListStorage;
        AudioBufferList* bufferList = nullptr;
        int maxFrames, numberOfChannels;
        bool isInterleaved;
        juce::AudioBuffer<float> scratchBuffer;
    };

    //==============================================================================
    void addAudioUnitBusses (bool isInput)
    {
        std::unique_ptr<NSMutableArray<AUAudioUnitBus*>, NSObjectDeleter> array ([[NSMutableArray<AUAudioUnitBus*> alloc] init]);
        AudioProcessor& processor = getAudioProcessor();
        const auto numWrapperBuses = AudioUnitHelpers::getBusCountForWrapper (processor, isInput);
        const auto numProcessorBuses = AudioUnitHelpers::getBusCount (processor, isInput);

        for (int i = 0; i < numWrapperBuses; ++i)
        {
            std::unique_ptr<AUAudioUnitBus, NSObjectDeleter> audioUnitBus;

            {
                const auto channels = numProcessorBuses <= i ? 2 : processor.getChannelCountOfBus (isInput, i);
                std::unique_ptr<AVAudioFormat, NSObjectDeleter> defaultFormat ([[AVAudioFormat alloc] initStandardFormatWithSampleRate: kDefaultSampleRate
                                                                                                                              channels: static_cast<AVAudioChannelCount> (channels)]);

                audioUnitBus.reset ([[AUAudioUnitBus alloc] initWithFormat: defaultFormat.get()
                                                                     error: nullptr]);
            }

            [array.get() addObject: audioUnitBus.get()];
        }

        (isInput ? inputBusses : outputBusses).reset ([[AUAudioUnitBusArray alloc] initWithAudioUnit: au
                                                                                             busType: (isInput ? AUAudioUnitBusTypeInput : AUAudioUnitBusTypeOutput)
                                                                                              busses: array.get()]);
    }

    // When parameters are discrete we need to use integer values.
    float getMaximumParameterValue (AudioProcessorParameter* juceParam)
    {
       #if JUCE_FORCE_LEGACY_PARAMETER_AUTOMATION_TYPE
        ignoreUnused (juceParam);
        return 1.0f;
       #else
        return juceParam->isDiscrete() ? (float) (juceParam->getNumSteps() - 1) : 1.0f;
       #endif
    }

    std::unique_ptr<AUParameter, NSObjectDeleter> createParameter (AudioProcessorParameter* parameter)
    {
        const String name (parameter->getName (512));

        AudioUnitParameterUnit unit = kAudioUnitParameterUnit_Generic;
        AudioUnitParameterOptions flags = (UInt32) (kAudioUnitParameterFlag_IsWritable
                                                  | kAudioUnitParameterFlag_IsReadable
                                                  | kAudioUnitParameterFlag_HasCFNameString
                                                  | kAudioUnitParameterFlag_ValuesHaveStrings);

       #if ! JUCE_FORCE_LEGACY_PARAMETER_AUTOMATION_TYPE
        flags |= (UInt32) kAudioUnitParameterFlag_IsHighResolution;
       #endif

        // Set whether the param is automatable (unnamed parameters aren't allowed to be automated).
        if (name.isEmpty() || ! parameter->isAutomatable())
            flags |= kAudioUnitParameterFlag_NonRealTime;

        const bool isParameterDiscrete = parameter->isDiscrete();

        if (! isParameterDiscrete)
            flags |= kAudioUnitParameterFlag_CanRamp;

        if (parameter->isMetaParameter())
            flags |= kAudioUnitParameterFlag_IsGlobalMeta;

        std::unique_ptr<NSMutableArray, NSObjectDeleter> valueStrings;

        // Is this a meter?
        if (((parameter->getCategory() & 0xffff0000) >> 16) == 2)
        {
            flags &= ~kAudioUnitParameterFlag_IsWritable;
            flags |= kAudioUnitParameterFlag_MeterReadOnly | kAudioUnitParameterFlag_DisplayLogarithmic;
            unit = kAudioUnitParameterUnit_LinearGain;
        }
        else
        {
           #if ! JUCE_FORCE_LEGACY_PARAMETER_AUTOMATION_TYPE
            if (parameter->isDiscrete())
            {
                unit = parameter->isBoolean() ? kAudioUnitParameterUnit_Boolean : kAudioUnitParameterUnit_Indexed;
                auto maxValue = getMaximumParameterValue (parameter);
                auto numSteps = parameter->getNumSteps();

                // Some hosts can't handle the huge numbers of discrete parameter values created when
                // using the default number of steps.
                jassert (numSteps != AudioProcessor::getDefaultNumParameterSteps());

                valueStrings.reset ([NSMutableArray new]);

                for (int i = 0; i < numSteps; ++i)
                    [valueStrings.get() addObject: juceStringToNS (parameter->getText ((float) i / maxValue, 0))];
            }
           #endif
        }

        AUParameterAddress address = generateAUParameterAddress (parameter);

       #if ! JUCE_FORCE_USE_LEGACY_PARAM_IDS
        // If you hit this assertion then you have either put a parameter in two groups or you are
        // very unlucky and the hash codes of your parameter ids are not unique.
        jassert (! paramMap.contains (static_cast<int64> (address)));

        paramAddresses.add (address);
        paramMap.set (static_cast<int64> (address), parameter->getParameterIndex());
       #endif

        auto getParameterIdentifier = [parameter]
        {
            if (auto* paramWithID = dynamic_cast<AudioProcessorParameterWithID*> (parameter))
                return paramWithID->paramID;

            // This could clash if any groups have been given integer IDs!
            return String (parameter->getParameterIndex());
        };

        std::unique_ptr<AUParameter, NSObjectDeleter> param;

        @try
        {
            // Create methods in AUParameterTree return unretained objects (!) -> see Apple header AUAudioUnitImplementation.h
            param.reset([[AUParameterTree createParameterWithIdentifier: juceStringToNS (getParameterIdentifier())
                                                                   name: juceStringToNS (name)
                                                                address: address
                                                                    min: 0.0f
                                                                    max: getMaximumParameterValue (parameter)
                                                                   unit: unit
                                                               unitName: nullptr
                                                                  flags: flags
                                                           valueStrings: valueStrings.get()
                                                    dependentParameters: nullptr]
                         retain]);
        }

        @catch (NSException* exception)
        {
            // Do you have duplicate identifiers in any of your groups or parameters,
            // or do your identifiers have unusual characters in them?
            jassertfalse;
        }

        [param.get() setValue: parameter->getDefaultValue()];

        [overviewParams.get() addObject: [NSNumber numberWithUnsignedLongLong: address]];

        return param;
    }

    std::unique_ptr<AUParameterGroup, NSObjectDeleter> createParameterGroup (AudioProcessorParameterGroup* group)
    {
        std::unique_ptr<NSMutableArray<AUParameterNode*>, NSObjectDeleter> children ([NSMutableArray<AUParameterNode*> new]);

        for (auto* node : *group)
        {
            if (auto* childGroup = node->getGroup())
                [children.get() addObject: createParameterGroup (childGroup).get()];
            else
                [children.get() addObject: createParameter (node->getParameter()).get()];
        }

        std::unique_ptr<AUParameterGroup, NSObjectDeleter> result;

        @try
        {
            // Create methods in AUParameterTree return unretained objects (!) -> see Apple header AUAudioUnitImplementation.h
            result.reset ([[AUParameterTree createGroupWithIdentifier: juceStringToNS (group->getID())
                                                                 name: juceStringToNS (group->getName())
                                                             children: children.get()]
                           retain]);
        }

        @catch (NSException* exception)
        {
            // Do you have duplicate identifiers in any of your groups or parameters,
            // or do your identifiers have unusual characters in them?
            jassertfalse;
        }

        return result;
    }

    void addParameters()
    {
        auto& processor = getAudioProcessor();
        juceParameters.update (processor, forceLegacyParamIDs);

        // This is updated when we build the tree.
        overviewParams.reset ([NSMutableArray<NSNumber*> new]);

        std::unique_ptr<NSMutableArray<AUParameterNode*>, NSObjectDeleter> topLevelNodes ([NSMutableArray<AUParameterNode*> new]);

        for (auto* node : processor.getParameterTree())
            if (auto* childGroup = node->getGroup())
                [topLevelNodes.get() addObject: createParameterGroup (childGroup).get()];
            else
                [topLevelNodes.get() addObject: createParameter (node->getParameter()).get()];

        @try
        {
            // Create methods in AUParameterTree return unretained objects (!) -> see Apple header AUAudioUnitImplementation.h
            paramTree.reset ([[AUParameterTree createTreeWithChildren: topLevelNodes.get()] retain]);
        }

        @catch (NSException* exception)
        {
            // Do you have duplicate identifiers in any of your groups or parameters,
            // or do your identifiers have unusual characters in them?
            jassertfalse;
        }

        paramObserver           = CreateObjCBlock (this, &JuceAudioUnitv3::valueChangedFromHost);
        paramProvider           = CreateObjCBlock (this, &JuceAudioUnitv3::getValue);
        stringFromValueProvider = CreateObjCBlock (this, &JuceAudioUnitv3::stringFromValue);
        valueFromStringProvider = CreateObjCBlock (this, &JuceAudioUnitv3::valueFromString);

        [paramTree.get() setImplementorValueObserver: paramObserver];
        [paramTree.get() setImplementorValueProvider: paramProvider];
        [paramTree.get() setImplementorStringFromValueCallback: stringFromValueProvider];
        [paramTree.get() setImplementorValueFromStringCallback: valueFromStringProvider];

        if (processor.hasEditor())
        {
            editorParamObserver = CreateObjCBlock (this, &JuceAudioUnitv3::valueChangedForObserver);
            editorObserverToken = [paramTree.get() tokenByAddingParameterObserver: editorParamObserver];
        }

        if ((bypassParam = processor.getBypassParameter()) != nullptr)
            bypassParam->addListener (this);
    }

    void setAudioProcessorParameter (AudioProcessorParameter* juceParam, float value)
    {
        if (value != juceParam->getValue())
        {
            juceParam->setValue (value);

            inParameterChangedCallback = true;
            juceParam->sendValueChangedMessageToListeners (value);
        }
    }

    void addPresets()
    {
        factoryPresets.reset ([[NSMutableArray<AUAudioUnitPreset*> alloc] init]);

        const int n = getAudioProcessor().getNumPrograms();

        for (int idx = 0; idx < n; ++idx)
        {
            String name = getAudioProcessor().getProgramName (idx);

            std::unique_ptr<AUAudioUnitPreset, NSObjectDeleter> preset ([[AUAudioUnitPreset alloc] init]);
            [preset.get() setName: juceStringToNS (name)];
            [preset.get() setNumber: static_cast<NSInteger> (idx)];

            [factoryPresets.get() addObject: preset.get()];
        }
    }

    //==============================================================================
    void allocateBusBuffer (bool isInput)
    {
        OwnedArray<BusBuffer>& busBuffers = isInput ? inBusBuffers : outBusBuffers;
        busBuffers.clear();

        const int n = AudioUnitHelpers::getBusCountForWrapper (getAudioProcessor(), isInput);
        const AUAudioFrameCount maxFrames = [getAudioUnit() maximumFramesToRender];

        for (int busIdx = 0; busIdx < n; ++busIdx)
            busBuffers.add (new BusBuffer ([(isInput ? inputBusses.get() : outputBusses.get()) objectAtIndexedSubscript: static_cast<unsigned int> (busIdx)],
                                           static_cast<int> (maxFrames)));
    }

    //==============================================================================
    void processEvents (const AURenderEvent *__nullable realtimeEventListHead, int numParams, AUEventSampleTime startTime)
    {
        ignoreUnused (numParams);

        for (const AURenderEvent* event = realtimeEventListHead; event != nullptr; event = event->head.next)
        {
            switch (event->head.eventType)
            {
                case AURenderEventMIDI:
                {
                    const AUMIDIEvent& midiEvent = event->MIDI;
                    midiMessages.addEvent (midiEvent.data, midiEvent.length, static_cast<int> (midiEvent.eventSampleTime - startTime));
                }
                break;

               #if JUCE_AUV3_MIDI_EVENT_LIST_SUPPORTED
                case AURenderEventMIDIEventList:
                {
                    const auto& list = event->MIDIEventsList.eventList;
                    auto* packet = &list.packet[0];

                    for (uint32_t i = 0; i < list.numPackets; ++i)
                    {
                        converter.dispatch (reinterpret_cast<const uint32_t*> (packet->words),
                                            reinterpret_cast<const uint32_t*> (packet->words + packet->wordCount),
                                            static_cast<int> (packet->timeStamp - (MIDITimeStamp) startTime),
                                            [this] (const MidiMessage& message) { midiMessages.addEvent (message, int (message.getTimeStamp())); });

                        packet = MIDIEventPacketNext (packet);
                    }
                }
                break;
               #endif

                case AURenderEventParameter:
                case AURenderEventParameterRamp:
                {
                    const AUParameterEvent& paramEvent = event->parameter;

                    if (auto* p = getJuceParameterForAUAddress (paramEvent.parameterAddress))
                    {
                        auto normalisedValue = paramEvent.value / getMaximumParameterValue (p);
                        setAudioProcessorParameter (p, normalisedValue);
                    }
                }
                break;

                case AURenderEventMIDISysEx:
                default:
                    break;
            }
        }
    }

    AUAudioUnitStatus renderCallback (AudioUnitRenderActionFlags* actionFlags, const AudioTimeStamp* timestamp, AUAudioFrameCount frameCount,
                                      NSInteger outputBusNumber, AudioBufferList* outputData, const AURenderEvent *__nullable realtimeEventListHead,
                                      AURenderPullInputBlock __nullable pullInputBlock)
    {
        auto& processor = getAudioProcessor();
        jassert (static_cast<int> (frameCount) <= getAudioProcessor().getBlockSize());

        const auto numProcessorBusesOut = AudioUnitHelpers::getBusCount (processor, false);

        if (timestamp != nullptr)
        {
            if ((timestamp->mFlags & kAudioTimeStampHostTimeValid) != 0)
            {
                const auto convertedTime = timeConversions.hostTimeToNanos (timestamp->mHostTime);
                getAudioProcessor().setHostTimeNanos (&convertedTime);
            }
        }

        struct AtEndOfScope
        {
            ~AtEndOfScope() { proc.setHostTimeNanos (nullptr); }
            AudioProcessor& proc;
        };

        const AtEndOfScope scope { getAudioProcessor() };

        if (lastTimeStamp.mSampleTime != timestamp->mSampleTime)
        {
            // process params and incoming midi (only once for a given timestamp)
            midiMessages.clear();

            const int numParams = juceParameters.getNumParameters();
            processEvents (realtimeEventListHead, numParams, static_cast<AUEventSampleTime> (timestamp->mSampleTime));

            lastTimeStamp = *timestamp;

            const auto numWrapperBusesIn    = AudioUnitHelpers::getBusCountForWrapper (processor, true);
            const auto numWrapperBusesOut   = AudioUnitHelpers::getBusCountForWrapper (processor, false);
            const auto numProcessorBusesIn  = AudioUnitHelpers::getBusCount (processor, true);

            // prepare buffers
            {
                for (int busIdx = 0; busIdx < numWrapperBusesOut; ++busIdx)
                {
                     BusBuffer& busBuffer = *outBusBuffers[busIdx];
                     const bool canUseDirectOutput =
                         (busIdx == outputBusNumber && outputData != nullptr && outputData->mNumberBuffers > 0);

                    busBuffer.prepare (frameCount, canUseDirectOutput ? outputData : nullptr);

                    if (numProcessorBusesOut <= busIdx)
                        AudioUnitHelpers::clearAudioBuffer (*busBuffer.get());
                }

                for (int busIdx = 0; busIdx < numWrapperBusesIn; ++busIdx)
                {
                    BusBuffer& busBuffer = *inBusBuffers[busIdx];
                    busBuffer.prepare (frameCount, busIdx < numWrapperBusesOut ? outBusBuffers[busIdx]->get() : nullptr);
                }

                audioBuffer.reset();
            }

            // pull inputs
            {
                for (int busIdx = 0; busIdx < numProcessorBusesIn; ++busIdx)
                {
                    BusBuffer& busBuffer = *inBusBuffers[busIdx];
                    AudioBufferList* buffer = busBuffer.get();

                    if (pullInputBlock == nullptr || pullInputBlock (actionFlags, timestamp, frameCount, busIdx, buffer) != noErr)
                        AudioUnitHelpers::clearAudioBuffer (*buffer);

                    if (actionFlags != nullptr && (*actionFlags & kAudioUnitRenderAction_OutputIsSilence) != 0)
                        AudioUnitHelpers::clearAudioBuffer (*buffer);
                }
            }

            // set buffer pointer to minimize copying
            {
                int chIdx = 0;

                for (int busIdx = 0; busIdx < numProcessorBusesOut; ++busIdx)
                {
                    BusBuffer& busBuffer = *outBusBuffers[busIdx];
                    AudioBufferList* buffer = busBuffer.get();

                    const bool interleaved = busBuffer.interleaved();
                    const int numChannels = busBuffer.numChannels();

                    const int* outLayoutMap = mapper.get (false, busIdx);

                    for (int ch = 0; ch < numChannels; ++ch)
                        audioBuffer.setBuffer (chIdx++, interleaved ? nullptr : static_cast<float*> (buffer->mBuffers[outLayoutMap[ch]].mData));
                }

                // use input pointers on remaining channels

                for (int busIdx = 0; chIdx < totalInChannels;)
                {
                    const int channelOffset = processor.getOffsetInBusBufferForAbsoluteChannelIndex (true, chIdx, busIdx);

                    BusBuffer& busBuffer = *inBusBuffers[busIdx];
                    AudioBufferList* buffer = busBuffer.get();

                    const int* inLayoutMap = mapper.get (true, busIdx);
                    audioBuffer.setBuffer (chIdx++, busBuffer.interleaved() ? nullptr : static_cast<float*> (buffer->mBuffers[inLayoutMap[channelOffset]].mData));
                }
            }

            // copy input
            {
                for (int busIdx = 0; busIdx < numProcessorBusesIn; ++busIdx)
                    audioBuffer.set (busIdx, *inBusBuffers[busIdx]->get(), mapper.get (true, busIdx));

                audioBuffer.clearUnusedChannels ((int) frameCount);
            }

            // process audio
            processBlock (audioBuffer.getBuffer (frameCount), midiMessages);

            // send MIDI
           #if JucePlugin_ProducesMidiOutput && JUCE_AUV3_MIDI_OUTPUT_SUPPORTED
            if (@available (macOS 10.13, iOS 11.0, *))
            {
                if (auto midiOut = midiOutputEventBlock)
                    for (const auto metadata : midiMessages)
                        if (isPositiveAndBelow (metadata.samplePosition, frameCount))
                            midiOut ((int64_t) metadata.samplePosition + (int64_t) (timestamp->mSampleTime + 0.5),
                                     0,
                                     metadata.numBytes,
                                     metadata.data);
            }
           #endif
        }

        // copy back
        if (outputBusNumber < numProcessorBusesOut && outputData != nullptr)
            audioBuffer.get ((int) outputBusNumber, *outputData, mapper.get (false, (int) outputBusNumber));

        return noErr;
    }

    void processBlock (juce::AudioBuffer<float>& buffer, MidiBuffer& midiBuffer) noexcept
    {
        auto& processor = getAudioProcessor();
        const ScopedLock sl (processor.getCallbackLock());

        if (processor.isSuspended())
            buffer.clear();
        else if (bypassParam == nullptr && [au shouldBypassEffect])
            processor.processBlockBypassed (buffer, midiBuffer);
        else
            processor.processBlock (buffer, midiBuffer);
    }

    //==============================================================================
    void valueChangedFromHost (AUParameter* param, AUValue value)
    {
        if (param != nullptr)
        {
            if (auto* p = getJuceParameterForAUAddress ([param address]))
            {
                auto normalisedValue = value / getMaximumParameterValue (p);
                setAudioProcessorParameter (p, normalisedValue);
            }
        }
    }

    AUValue getValue (AUParameter* param)
    {
        if (param != nullptr)
        {
            if (auto* p = getJuceParameterForAUAddress ([param address]))
                return p->getValue() * getMaximumParameterValue (p);
        }

        return 0;
    }

    void valueChangedForObserver (AUParameterAddress, AUValue)
    {
        // this will have already been handled by valueChangedFromHost
    }

    NSString* stringFromValue (AUParameter* param, const AUValue* value)
    {
        String text;

        if (param != nullptr && value != nullptr)
        {
            if (auto* p = getJuceParameterForAUAddress ([param address]))
            {
                if (LegacyAudioParameter::isLegacy (p))
                    text = String (*value);
                else
                    text = p->getText (*value / getMaximumParameterValue (p), 0);
            }
        }

        return juceStringToNS (text);
    }

    AUValue valueFromString (AUParameter* param, NSString* str)
    {
        if (param != nullptr && str != nullptr)
        {
            if (auto* p = getJuceParameterForAUAddress ([param address]))
            {
                const String text (nsStringToJuce (str));

                if (LegacyAudioParameter::isLegacy (p))
                    return text.getFloatValue();
                else
                    return p->getValueForText (text) * getMaximumParameterValue (p);
            }
        }

        return 0;
    }

    //==============================================================================
    // this is only ever called for the bypass parameter
    void parameterValueChanged (int, float newValue) override
    {
        JuceAudioUnitv3Base::setShouldBypassEffect (newValue != 0.0f);
    }

    void parameterGestureChanged (int, bool) override {}

    //==============================================================================
    inline AUParameterAddress getAUParameterAddressForIndex (int paramIndex) const noexcept
    {
       #if JUCE_FORCE_USE_LEGACY_PARAM_IDS
        return static_cast<AUParameterAddress> (paramIndex);
       #else
        return paramAddresses.getReference (paramIndex);
       #endif
    }

    inline int getJuceParameterIndexForAUAddress (AUParameterAddress address) const noexcept
    {
       #if JUCE_FORCE_USE_LEGACY_PARAM_IDS
        return static_cast<int> (address);
       #else
        return paramMap[static_cast<int64> (address)];
       #endif
    }

    AUParameterAddress generateAUParameterAddress (AudioProcessorParameter* param) const
    {
        const String& juceParamID = LegacyAudioParameter::getParamID (param, forceLegacyParamIDs);

        return static_cast<AUParameterAddress> (forceLegacyParamIDs ? juceParamID.getIntValue()
                                                                    : juceParamID.hashCode64());
    }

    AudioProcessorParameter* getJuceParameterForAUAddress (AUParameterAddress address) const noexcept
    {
        return juceParameters.getParamForIndex (getJuceParameterIndexForAUAddress (address));
    }

    //==============================================================================
    static const double kDefaultSampleRate;

    AudioProcessorHolder::Ptr processorHolder;

    int totalInChannels, totalOutChannels;

    CoreAudioTimeConversions timeConversions;
    std::unique_ptr<AUAudioUnitBusArray, NSObjectDeleter> inputBusses, outputBusses;

    ObjCBlock<AUImplementorValueObserver> paramObserver;
    ObjCBlock<AUImplementorValueProvider> paramProvider;
    ObjCBlock<AUImplementorStringFromValueCallback> stringFromValueProvider;
    ObjCBlock<AUImplementorValueFromStringCallback> valueFromStringProvider;

   #if ! JUCE_FORCE_USE_LEGACY_PARAM_IDS
    Array<AUParameterAddress> paramAddresses;
    HashMap<int64, int> paramMap;
   #endif
    LegacyAudioParametersWrapper juceParameters;

    // to avoid recursion on parameter changes, we need to add an
    // editor observer to do the parameter changes
    ObjCBlock<AUParameterObserver> editorParamObserver;
    AUParameterObserverToken editorObserverToken;

    std::unique_ptr<AUParameterTree, NSObjectDeleter> paramTree;
    std::unique_ptr<NSMutableArray<NSNumber*>, NSObjectDeleter> overviewParams, channelCapabilities;

    std::unique_ptr<NSMutableArray<AUAudioUnitPreset*>, NSObjectDeleter> factoryPresets;

    ObjCBlock<AUInternalRenderBlock> internalRenderBlock;

    AudioUnitHelpers::CoreAudioBufferList audioBuffer;
    AudioUnitHelpers::ChannelRemapper mapper;

    OwnedArray<BusBuffer> inBusBuffers, outBusBuffers;
    MidiBuffer midiMessages;
    AUMIDIOutputEventBlock midiOutputEventBlock = nullptr;

   #if JUCE_AUV3_MIDI_EVENT_LIST_SUPPORTED
    ump::ToBytestreamDispatcher converter { 2048 };
   #endif

    ObjCBlock<AUHostMusicalContextBlock> hostMusicalContextCallback;
    ObjCBlock<AUHostTransportStateBlock> hostTransportStateCallback;

    AudioTimeStamp lastTimeStamp;
    CurrentPositionInfo lastAudioHead;

    String contextName;

    ThreadLocalValue<bool> inParameterChangedCallback;
   #if JUCE_FORCE_USE_LEGACY_PARAM_IDS
    static constexpr bool forceLegacyParamIDs = true;
   #else
    static constexpr bool forceLegacyParamIDs = false;
   #endif
    AudioProcessorParameter* bypassParam = nullptr;
};

const double JuceAudioUnitv3::kDefaultSampleRate = 44100.0;

JuceAudioUnitv3Base* JuceAudioUnitv3Base::create (AUAudioUnit* audioUnit, AudioComponentDescription descr, AudioComponentInstantiationOptions options, NSError** error)
{
    PluginHostType::jucePlugInClientCurrentWrapperType = AudioProcessor::wrapperType_AudioUnitv3;
    return new JuceAudioUnitv3 (audioUnit, descr, options, error);
}

#if JUCE_IOS
namespace juce
{
struct UIViewPeerControllerReceiver
{
    virtual ~UIViewPeerControllerReceiver();
    virtual void setViewController (UIViewController*) = 0;
};
}
#endif

//==============================================================================
class JuceAUViewController
{
public:
    JuceAUViewController (AUViewController<AUAudioUnitFactory>* p)
        : myself (p)
    {
        PluginHostType::jucePlugInClientCurrentWrapperType = AudioProcessor::wrapperType_AudioUnitv3;
        initialiseJuce_GUI();
    }

    ~JuceAUViewController()
    {
        JUCE_ASSERT_MESSAGE_THREAD

        if (processorHolder.get() != nullptr)
            JuceAudioUnitv3::removeEditor (getAudioProcessor());
    }

    //==============================================================================
    void loadView()
    {
        JUCE_ASSERT_MESSAGE_THREAD

        if (AudioProcessor* p = createPluginFilterOfType (AudioProcessor::wrapperType_AudioUnitv3))
        {
            processorHolder = new AudioProcessorHolder (p);
            auto& processor = getAudioProcessor();

            if (processor.hasEditor())
            {
                if (AudioProcessorEditor* editor = processor.createEditorIfNeeded())
                {
                    preferredSize = editor->getBounds();

                    JUCE_IOS_MAC_VIEW* view = [[[JUCE_IOS_MAC_VIEW alloc] initWithFrame: convertToCGRect (editor->getBounds())] autorelease];
                    [myself setView: view];

                   #if JUCE_IOS
                    editor->setVisible (false);
                   #else
                    editor->setVisible (true);
                   #endif

                    editor->addToDesktop (0, view);

                   #if JUCE_IOS
                    if (JUCE_IOS_MAC_VIEW* peerView = [[[myself view] subviews] objectAtIndex: 0])
                        [peerView setContentMode: UIViewContentModeTop];

                    if (auto* peer = dynamic_cast<UIViewPeerControllerReceiver*> (editor->getPeer()))
                        peer->setViewController (myself);
                   #endif
                }
            }
        }
    }

    void viewDidLayoutSubviews()
    {
        if (auto holder = processorHolder.get())
        {
            if ([myself view] != nullptr)
            {
                if (AudioProcessorEditor* editor = getAudioProcessor().getActiveEditor())
                {
                    if (holder->viewConfiguration != nullptr)
                        editor->hostMIDIControllerIsAvailable (holder->viewConfiguration->hostHasMIDIController);

                    editor->setBounds (convertToRectInt ([[myself view] bounds]));

                    if (JUCE_IOS_MAC_VIEW* peerView = [[[myself view] subviews] objectAtIndex: 0])
                    {
                       #if JUCE_IOS
                        [peerView setNeedsDisplay];
                       #else
                        [peerView setNeedsDisplay: YES];
                       #endif
                    }
                }
            }
        }
    }

    void didReceiveMemoryWarning()
    {
        if (auto ptr = processorHolder.get())
            if (auto* processor = ptr->get())
                processor->memoryWarningReceived();
    }

    void viewDidAppear (bool)
    {
        if (processorHolder.get() != nullptr)
            if (AudioProcessorEditor* editor = getAudioProcessor().getActiveEditor())
                editor->setVisible (true);
    }

    void viewDidDisappear (bool)
    {
        if (processorHolder.get() != nullptr)
            if (AudioProcessorEditor* editor = getAudioProcessor().getActiveEditor())
                editor->setVisible (false);
    }

    CGSize getPreferredContentSize() const
    {
        return CGSizeMake (static_cast<float> (preferredSize.getWidth()),
                           static_cast<float> (preferredSize.getHeight()));
    }

    //==============================================================================
    AUAudioUnit* createAudioUnit (const AudioComponentDescription& descr, NSError** error)
    {
        const auto holder = [&]
        {
            if (auto initialisedHolder = processorHolder.get())
                return initialisedHolder;

            waitForExecutionOnMainThread ([this] { [myself view]; });
            return processorHolder.get();
        }();

        if (holder == nullptr)
            return nullptr;

        return [(new JuceAudioUnitv3 (holder, descr, 0, error))->getAudioUnit() autorelease];
    }

private:
    template <typename Callback>
    static void waitForExecutionOnMainThread (Callback&& callback)
    {
        if (MessageManager::getInstance()->isThisTheMessageThread())
        {
            callback();
            return;
        }

        std::promise<void> promise;

        MessageManager::callAsync ([&]
        {
            callback();
            promise.set_value();
        });

        promise.get_future().get();
    }

    // There's a chance that createAudioUnit will be called from a background
    // thread while the processorHolder is being updated on the main thread.
    class LockedProcessorHolder
    {
    public:
        AudioProcessorHolder::Ptr get() const
        {
            const ScopedLock lock (mutex);
            return holder;
        }

        LockedProcessorHolder& operator= (const AudioProcessorHolder::Ptr& other)
        {
            const ScopedLock lock (mutex);
            holder = other;
            return *this;
        }

    private:
        mutable CriticalSection mutex;
        AudioProcessorHolder::Ptr holder;
    };

    //==============================================================================
    AUViewController<AUAudioUnitFactory>* myself;
    LockedProcessorHolder processorHolder;
    Rectangle<int> preferredSize { 1, 1 };

    //==============================================================================
    AudioProcessor& getAudioProcessor() const noexcept       { return **processorHolder.get(); }
};

//==============================================================================
// necessary glue code
@interface JUCE_VIEWCONTROLLER_OBJC_NAME (JucePlugin_AUExportPrefix) : AUViewController<AUAudioUnitFactory>
@end

@implementation JUCE_VIEWCONTROLLER_OBJC_NAME (JucePlugin_AUExportPrefix)
{
    std::unique_ptr<JuceAUViewController> cpp;
}

- (instancetype) initWithNibName: (nullable NSString*) nib bundle: (nullable NSBundle*) bndl { self = [super initWithNibName: nib bundle: bndl]; cpp.reset (new JuceAUViewController (self)); return self; }
- (void) loadView                { cpp->loadView(); }
- (AUAudioUnit *) createAudioUnitWithComponentDescription: (AudioComponentDescription) desc error: (NSError **) error { return cpp->createAudioUnit (desc, error); }
- (CGSize) preferredContentSize  { return cpp->getPreferredContentSize(); }

// NSViewController and UIViewController have slightly different names for this function
- (void) viewDidLayoutSubviews   { cpp->viewDidLayoutSubviews(); }
- (void) viewDidLayout           { cpp->viewDidLayoutSubviews(); }

- (void) didReceiveMemoryWarning { cpp->didReceiveMemoryWarning(); }
#if JUCE_IOS
- (void) viewDidAppear: (BOOL) animated { cpp->viewDidAppear (animated); [super viewDidAppear:animated]; }
- (void) viewDidDisappear: (BOOL) animated { cpp->viewDidDisappear (animated); [super viewDidDisappear:animated]; }
#endif
@end

//==============================================================================
#if JUCE_IOS
JUCE_BEGIN_IGNORE_WARNINGS_GCC_LIKE ("-Wmissing-prototypes")

bool JUCE_CALLTYPE juce_isInterAppAudioConnected() { return false; }
void JUCE_CALLTYPE juce_switchToHostApplication()  {}
Image JUCE_CALLTYPE juce_getIAAHostIcon (int)      { return {}; }

JUCE_END_IGNORE_WARNINGS_GCC_LIKE
#endif

JUCE_END_IGNORE_WARNINGS_GCC_LIKE
#endif