AU Client: Tweak saved version number of presets before restoring to allow restoring AUv3 state

modules/juce_audio_plugin_client/juce_audio_plugin_client_AU_1.mm

@@ -785,6 +785,27 @@ public:
             // Remove the data entry from the state to prevent the superclass loading the parameters
             CFUniquePtr<CFMutableDictionaryRef> copyWithoutData (CFDictionaryCreateMutableCopy (nullptr, 0, (CFDictionaryRef) inData));
             CFDictionaryRemoveValue (copyWithoutData.get(), CFSTR (kAUPresetDataKey));
+
+            auto* originalVersion = static_cast<CFNumberRef> (CFDictionaryGetValue (copyWithoutData.get(), CFSTR (kAUPresetVersionKey)));
+            if (originalVersion != nullptr && CFGetTypeID (originalVersion) == CFNumberGetTypeID())
+            {
+                SInt32 value = 0;
+                CFNumberGetValue (originalVersion, kCFNumberSInt32Type, &value);
+
+                // Data with a version of "1" is generated by AUv3 plug-ins.
+                // This data appears to be compatible with RestoreState below, but RestoreState
+                // fails when "version" is not 0.
+                // We only overwrite the version if it is 1 so that if future preset versions are
+                // completely incompatible, RestoreState will be bypassed rather than passed data
+                // which could put the plugin into a broken state.
+                if (value == 1)
+                {
+                    const SInt32 zero = 0;
+                    CFUniquePtr<CFNumberRef> newVersion (CFNumberCreate (nullptr, kCFNumberSInt32Type, &zero));
+                    CFDictionarySetValue (copyWithoutData.get(), CFSTR (kAUPresetVersionKey), newVersion.get());
+                }
+            }
+
             ComponentResult err = MusicDeviceBase::RestoreState (copyWithoutData.get());
 
             if (err != noErr)