FileChooser: Avoid potential issue when viewDidDismiss and file selection callbacks are interleaved

viewDidDisappear may be called when a file is successfully selected.
presentationControllerDidDismiss is only called when the controller is
dismissed manually by the user, e.g. by tapping outside the sheet, or by
dragging it away.

Checking for sheet dismissal is necessary in iOS 15, but not in iOS 17.
In iOS 17, tapping outside the file chooser causes a callback to
documentPickerWasCancelled instead.

modules/juce_gui_basics/filebrowser/juce_FileChooser.cpp

@@ -259,15 +259,14 @@ URL FileChooser::getURLResult() const
 
 void FileChooser::finished (const Array<URL>& asyncResults)
 {
-     std::function<void (const FileChooser&)> callback;
-     std::swap (callback, asyncCallback);
+    const auto callback = std::exchange (asyncCallback, nullptr);
 
-     results = asyncResults;
+    results = asyncResults;
 
-     pimpl.reset();
+    pimpl.reset();
 
-     if (callback)
-         callback (*this);
+    if (callback)
+        callback (*this);
 }
 
 #if ! JUCE_ANDROID

modules/juce_gui_basics/native/juce_FileChooser_ios.mm

@@ -27,7 +27,7 @@
 - (void) setParent: (FileChooser::Native*) ptr;
 @end
 
-@interface FileChooserDelegateClass : NSObject<UIDocumentPickerDelegate>
+@interface FileChooserDelegateClass : NSObject<UIDocumentPickerDelegate, UIAdaptivePresentationControllerDelegate>
 - (id) initWithOwner: (FileChooser::Native*) owner;
 @end
 
@@ -42,7 +42,6 @@ namespace juce
 //==============================================================================
 class FileChooser::Native final : public FileChooser::Pimpl,
                                   public detail::NativeModalWrapperComponent,
-                                  public AsyncUpdater,
                                   public std::enable_shared_from_this<Native>
 {
 public:
@@ -86,16 +85,9 @@ public:
        #endif
     }
 
-    void handleAsyncUpdate() override
-    {
-        pickerWasCancelled();
-    }
-
     //==============================================================================
     void didPickDocumentsAtURLs (NSArray<NSURL*>* urls)
     {
-        cancelPendingUpdate();
-
         const auto isWriting =  controller.get().documentPickerMode == UIDocumentPickerModeExportToService
                              || controller.get().documentPickerMode == UIDocumentPickerModeMoveToService;
         const auto accessOptions = isWriting ? 0 : NSFileCoordinatorReadingWithoutChanges;
@@ -223,12 +215,14 @@ private:
 
         [controller.get() setDelegate: delegate.get()];
 
+        if (auto* pc = [controller.get() presentationController])
+            [pc setDelegate: delegate.get()];
+
         displayNativeWindowModally (fileChooser.parent);
     }
 
     void passResultsToInitiator (Array<URL> urls)
     {
-        cancelPendingUpdate();
         exitModalState (0);
 
         // If the caller attempts to show a platform-native dialog box inside the results callback (e.g. in the DialogsDemo)
@@ -310,7 +304,7 @@ private:
 
     //==============================================================================
     FileChooser& owner;
-    NSUniquePtr<NSObject<UIDocumentPickerDelegate>> delegate;
+    NSUniquePtr<NSObject<UIDocumentPickerDelegate, UIAdaptivePresentationControllerDelegate>> delegate;
     NSUniquePtr<FileChooserControllerClass> controller;
 
     //==============================================================================
@@ -351,14 +345,6 @@ std::shared_ptr<FileChooser::Pimpl> FileChooser::showPlatformDialog (FileChooser
     ptr = parent->weak_from_this();
 }
 
-- (void) viewDidDisappear: (BOOL) animated
-{
-    [super viewDidDisappear: animated];
-
-    if (auto nativeParent = ptr.lock())
-        nativeParent->triggerAsyncUpdate();
-}
-
 @end
 
 @implementation FileChooserDelegateClass
@@ -393,4 +379,10 @@ JUCE_END_IGNORE_WARNINGS_GCC_LIKE
         owner->pickerWasCancelled();
 }
 
+- (void) presentationControllerDidDismiss: (UIPresentationController *) presentationController
+{
+    if (owner != nullptr)
+        owner->pickerWasCancelled();
+}
+
 @end