iOS: Fixed a crash due to a dangling JuceUIViewController when updating screen bounds

modules/juce_gui_basics/native/juce_ios_UIViewComponentPeer.mm

@@ -101,6 +101,23 @@ namespace Orientations
     }
 }
 
+struct AsyncBoundsUpdater  : public AsyncUpdater
+{
+    AsyncBoundsUpdater (UIViewController* vc)
+        : viewController (vc)
+    {
+    }
+
+    ~AsyncBoundsUpdater() override
+    {
+        cancelPendingUpdate();
+    }
+
+    void handleAsyncUpdate() override;
+
+    UIViewController* viewController;
+};
+
 //==============================================================================
 } // namespace juce
 
@@ -134,8 +151,12 @@ using namespace juce;
 //==============================================================================
 @interface JuceUIViewController : UIViewController
 {
+@public
+    std::unique_ptr<AsyncBoundsUpdater> boundsUpdater;
 }
 
+- (JuceUIViewController*) init;
+
 - (NSUInteger) supportedInterfaceOrientations;
 - (BOOL) shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation) interfaceOrientation;
 - (void) willRotateToInterfaceOrientation: (UIInterfaceOrientation) toInterfaceOrientation duration: (NSTimeInterval) duration;
@@ -342,6 +363,11 @@ static void sendScreenBoundsUpdate (JuceUIViewController* c)
         juceView->owner->updateTransformAndScreenBounds();
 }
 
+void AsyncBoundsUpdater::handleAsyncUpdate()
+{
+    sendScreenBoundsUpdate ((JuceUIViewController*) viewController);
+}
+
 static bool isKioskModeView (JuceUIViewController* c)
 {
     JuceUIView* juceView = (JuceUIView*) [c view];
@@ -358,6 +384,15 @@ MultiTouchMapper<UITouch*> UIViewComponentPeer::currentTouches;
 //==============================================================================
 @implementation JuceUIViewController
 
+- (JuceUIViewController*) init
+{
+    self = [super init];
+
+    boundsUpdater = std::make_unique<AsyncBoundsUpdater> (self);
+
+    return self;
+}
+
 - (NSUInteger) supportedInterfaceOrientations
 {
     return Orientations::getSupportedOrientations();
@@ -390,7 +425,8 @@ MultiTouchMapper<UITouch*> UIViewComponentPeer::currentTouches;
 
     // On some devices the screen-size isn't yet updated at this point, so also trigger another
     // async update to double-check..
-    MessageManager::callAsync ([=] { sendScreenBoundsUpdate (self); });
+    if (boundsUpdater != nullptr)
+        boundsUpdater->triggerAsyncUpdate();
 }
 
 - (BOOL) prefersStatusBarHidden
@@ -629,6 +665,8 @@ UIViewComponentPeer::~UIViewComponentPeer()
     currentTouches.deleteAllTouchesForPeer (this);
     Desktop::getInstance().removeFocusChangeListener (this);
 
+    ((JuceUIViewController*) controller)->boundsUpdater = nullptr;
+
     view->owner = nullptr;
     [view removeFromSuperview];
     [view release];