Fixing more UIKit memory leaks

Frameworks/UIKit/UIButton.mm

@@ -184,7 +184,7 @@ - (void)_initUIButton {
     _contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;
     _contentHorizontalAlignment = UIControlContentHorizontalAlignmentCenter;
 
-    __block UIButton* weakSelf = self;
+    __weak UIButton* weakSelf = self;
     XamlControls::HookButtonPointerEvents(_xamlButton,
                                           ^(RTObject* sender, WUXIPointerRoutedEventArgs* e) {
                                               // We mark the event as handled here. The method _processPointerPressedCallback

Frameworks/UIKit/XamlControls.mm

@@ -27,7 +27,9 @@
 // Button
 ////////////////////////////////////////////////////////////////////////////////////
 WXCButton* CreateButton() {
-    ComPtr<IInspectable> inspectable(XamlCreateButton());
+    ComPtr<IInspectable> inspectable;
+    // Use Attach for transfer-ownership semantics, else we +1 and leak
+    inspectable.Attach(XamlCreateButton());
     return _createRtProxy([WXCButton class], inspectable.Get());
 }
 
@@ -53,7 +55,9 @@ void HookLayoutEvent(WXCButton* button, WUXIPointerEventHandler layoutHook) {
 // ContentDialog
 ////////////////////////////////////////////////////////////////////////////////////
 WXCContentDialog* CreateContentDialog() {
-    ComPtr<IInspectable> inspectable(XamlCreateContentDialog());
+    ComPtr<IInspectable> inspectable;
+    // Use Attach for transfer-ownership semantics, else we +1 and leak
+    inspectable.Attach(XamlCreateContentDialog());
     return _createRtProxy([WXCContentDialog class], inspectable.Get());
 }
 
@@ -95,7 +99,9 @@ void XamlContentDialogSetDestructiveButtonIndex(WXCContentDialog* contentDialog,
 // Label
 ////////////////////////////////////////////////////////////////////////////////////
 WXCGrid* CreateLabel() {
-    Microsoft::WRL::ComPtr<IInspectable> inspectable(XamlCreateLabel());
+    Microsoft::WRL::ComPtr<IInspectable> inspectable;
+    // Use Attach for transfer-ownership semantics, else we +1 and leak
+    inspectable.Attach(XamlCreateLabel());
     return _createRtProxy([WXCGrid class], inspectable.Get());
 }
 

tests/functionaltests/FunctionalTests.cpp

@@ -476,6 +476,7 @@ extern void UIActivityIndicatorViewGetXamlElement();
 
 extern void UIButtonCreateXamlElement();
 extern void UIButtonGetXamlElement();
+extern void UIButtonCheckForLeaks();
 extern void UIButtonTitleColorChanged();
 extern void UIButtonTextChanged();
 
@@ -606,6 +607,10 @@ class UIKitTests {
         FrameworkHelper::RunOnUIThread(&UIButtonGetXamlElement);
     }
 
+    TEST_METHOD(UIButton_CheckForLeaks) {
+        UIButtonCheckForLeaks();
+    }
+
     TEST_METHOD(UIButton_TitleColorChanged) {
         UIButtonTitleColorChanged();
     }

tests/functionaltests/Tests/UIKitTests/UIButtonTests.mm

@@ -38,6 +38,63 @@
     ASSERT_TRUE([backingElement isKindOfClass:[WXFrameworkElement class]]);
 }
 
+@interface UIDeallocTestButton : UIButton {
+    std::shared_ptr<UXEvent> _event;
+}
+@end
+
+@implementation UIDeallocTestButton
+
+- (void)setDeallocEvent:(std::shared_ptr<UXEvent>)event {
+    _event = event;
+}
+
+-(void)dealloc {
+    _event->Set();
+    [super dealloc];
+}
+@end
+
+TEST(UIButton, CheckForLeaks) {
+    Microsoft::WRL::WeakRef weakXamlElement;
+    {
+        __block UIButtonWithControlsViewController* buttonVC = [[UIButtonWithControlsViewController alloc] init];
+        UXTestAPI::ViewControllerPresenter testHelper(buttonVC);
+
+        __block UIDeallocTestButton* testButton = nil;
+        __block auto event = UXEvent::CreateAuto();
+
+        // Create and render the button
+        dispatch_sync(dispatch_get_main_queue(), ^{
+            testButton = [[UIDeallocTestButton alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
+            testButton.backgroundColor = [UIColor redColor];
+            [testButton setDeallocEvent:event];
+            [buttonVC.view addSubview:testButton];
+        });
+
+        // Grab a weak reference to the backing Xaml element
+        Microsoft::WRL::ComPtr<IInspectable> xamlElement([[testButton xamlElement] comObj]);
+        ASSERT_TRUE_MSG(SUCCEEDED(xamlElement.AsWeak(&weakXamlElement)), "Failed to acquire a weak reference to the backing Xaml element.");
+        xamlElement = nullptr;
+
+        // Free the button
+        dispatch_sync(dispatch_get_main_queue(), ^{
+            // Nil out testButton and remove it from its superview
+            [testButton removeFromSuperview];
+            [testButton release];
+            testButton = nil;
+        });
+
+        // Validate that dealloc was called
+        ASSERT_TRUE_MSG(event->Wait(c_testTimeoutInSec), "FAILED: Waiting for dealloc call failed!");
+    }
+
+    // Validate that we can no longer acquire a strong reference to the UIButton's backing Xaml element
+    Microsoft::WRL::ComPtr<IInspectable> xamlElement;
+    weakXamlElement.As(&xamlElement);
+    ASSERT_EQ_MSG(xamlElement.Get(), nullptr, "Unexpectedly able to reacquire a strong reference to the backing Xaml element.");
+}
+
 TEST(UIButton, TitleColorChanged) {
     __block auto uxEvent = UXEvent::CreateManual();
     __block auto xamlSubscriber = std::make_shared<XamlEventSubscription>();