[iOS]Fix: FlyoutPage memory leak (#28769)

* fix

* enable Bugzilla31255Test

* add device test

* make _element a weak reference directly

* fix device test

* Use AssertMemoryTest in UITest

Author: bhavanesh2001

src/Controls/src/Core/Compatibility/Handlers/FlyoutPage/iOS/PhoneFlyoutPageRenderer.cs

@@ -17,7 +17,7 @@ public class PhoneFlyoutPageRenderer : UIViewController, IPlatformViewHandler
 	{
 		UIView _clickOffView;
 		UIViewController _detailController;
-		VisualElement _element;
+		WeakReference<VisualElement> _element;
 		bool _disposed;
 
 		UIViewController _flyoutController;
@@ -75,7 +75,7 @@ bool Presented
 			get { return _presented; }
 		}
 
-		public VisualElement Element => _viewHandlerWrapper.Element ?? _element;
+		public VisualElement Element => _viewHandlerWrapper.Element ?? _element?.GetTargetOrDefault();
 
 		public event EventHandler<VisualElementChangedEventArgs> ElementChanged;
 
@@ -100,7 +100,7 @@ public void SetElement(VisualElement element)
 			_clickOffView = new UIView();
 			_clickOffView.BackgroundColor = new Color(0, 0, 0, 0).ToPlatform();
 			_viewHandlerWrapper.SetVirtualView(element, OnElementChanged, false);
-			_element = element;
+			_element = new(element);
 
 			if (_intialLayoutFinished)
 			{
@@ -269,9 +269,7 @@ protected override void Dispose(bool disposing)
 				}
 
 				EmptyContainers();
-
-				Page.SendDisappearing();
-
+			    _element = null;
 				_disposed = true;
 			}
 

src/Controls/tests/DeviceTests/Elements/FlyoutPage/FlyoutPageTests.cs

@@ -252,6 +252,39 @@ await CreateHandlerAndAddToWindow<FlyoutViewHandler>(flyoutPage, async (handler)
 			});
 		}
 
+		[Fact(DisplayName = "FlyoutPage as Modal Does Not Leak")]
+		public async Task DoesNotLeakAsModal()
+		{
+			SetupBuilder();
+
+			var references = new List<WeakReference>();
+			var launcherPage = new ContentPage();
+			var window = new Window(launcherPage);
+
+			await CreateHandlerAndAddToWindow<WindowHandlerStub>(window, async handler =>
+			{
+				var flyoutPage = new FlyoutPage
+				{
+					Flyout = new ContentPage
+					{
+						Title = "Flyout",
+						IconImageSource = "icon.png"
+					},
+					Detail = new ContentPage { Title = "Detail" }
+				};
+
+				await launcherPage.Navigation.PushModalAsync(flyoutPage, true);
+
+				references.Add(new WeakReference(flyoutPage));
+				references.Add(new WeakReference(flyoutPage.Flyout));
+				references.Add(new WeakReference(flyoutPage.Detail));
+
+				await launcherPage.Navigation.PopModalAsync();
+			});
+
+			await AssertionExtensions.WaitForGC(references.ToArray());
+		}	
+
 		bool CanDeviceDoSplitMode(FlyoutPage page)
 		{
 			return ((IFlyoutPageController)page).ShouldShowSplitMode;

src/Controls/tests/TestCases.HostApp/Issues/Bugzilla/Bugzilla31255.cs

@@ -18,7 +18,8 @@ public MainPage()
 				{
 					VerticalOptions = LayoutOptions.Center,
 					HorizontalTextAlignment = TextAlignment.Center,
-					Text = "Page 1"
+					Text = "Page 1",
+					AutomationId = "MauiLabel"
 				});
 
 				Content = stack;
@@ -48,8 +49,7 @@ async void StartTrackPage2()
 			{
 				while (true)
 				{
-					((Label)((StackLayout)Content).Children[0]).Text =
-							string.Format("Page1. But Page2 IsAlive = {0}", _page2Tracker.IsAlive);
+					((Label)((StackLayout)Content).Children[0]).Text = _page2Tracker.IsAlive ? "Failed" : "Success";
 					await Task.Delay(1000);
 					GarbageCollectionHelper.Collect();
 				}
@@ -60,12 +60,12 @@ public class Page2 : FlyoutPage
 			{
 				public Page2()
 				{
-					Flyout = new Page()
+					Flyout = new ContentPage
 					{
 						Title = "Flyout",
 						IconImageSource = "Icon.png"
 					};
-					Detail = new Page() { Title = "Detail" };
+					Detail = new ContentPage() { Title = "Detail" };
 				}
 
 				protected override async void OnAppearing()
@@ -75,6 +75,10 @@ protected override async void OnAppearing()
 					await Task.Delay(1000);
 					await Navigation.PopModalAsync();
 				}
+				protected override void OnDisappearing()
+				{
+					base.OnDisappearing();
+				}
 			}
 		}
 	}

src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Bugzilla/Bugzilla31255.cs

@@ -1,5 +1,4 @@
-#if IOS
-using NUnit.Framework;
+using NUnit.Framework;
 using UITest.Appium;
 using UITest.Core;
 
@@ -14,15 +13,12 @@ public Bugzilla31255(TestDevice testDevice) : base(testDevice)
 		public override string Issue => "Flyout's page Icon cause memory leak after FlyoutPage is popped out by holding on page";
 
 		[Test]
-		[Ignore("The sample is crashing. More information: https://github.com/dotnet/maui/issues/21206")]
 		[Category(UITestCategories.Navigation)]
 		[Category(UITestCategories.Compatibility)]
-		public async Task Bugzilla31255Test()
+		public void Bugzilla31255Test()
 		{
 			App.Screenshot("I am at Bugzilla 31255");
-			await Task.Delay(5000);
-			App.WaitForNoElement("Page1. But Page2 IsAlive = False");
+			App.AssertMemoryTest();
 		}
 	}
-}
-#endif
+}