[leak-fix] Fix ScrollView.Scrolled memory leak (Fixes #36481)

src/Controls/src/Core/PublicAPI/net-android/PublicAPI.Unshipped.txt

@@ -26,3 +26,4 @@ override Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRenderer.OnH
 override Microsoft.Maui.Controls.Handlers.Items.MauiRecyclerView<TItemsView, TAdapter, TItemsViewSource>.OnSizeChanged(int w, int h, int oldw, int oldh) -> void
 ~override Microsoft.Maui.Controls.SwipeItems.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Label.~Label() -> void
+Microsoft.Maui.Controls.SwipeView.~SwipeView() -> void

src/Controls/src/Core/PublicAPI/net-ios/PublicAPI.Unshipped.txt

@@ -16,6 +16,7 @@ override Microsoft.Maui.Controls.Handlers.Items2.StructuredItemsViewController2<
 Microsoft.Maui.Controls.IndicatorView.~IndicatorView() -> void
 ~override Microsoft.Maui.Controls.SwipeItems.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Label.~Label() -> void
+Microsoft.Maui.Controls.SwipeView.~SwipeView() -> void
 override Microsoft.Maui.Controls.Handlers.Items.MauiCollectionView.LayoutSubviews() -> void
 ~override Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRenderer.TraitCollectionDidChange(UIKit.UITraitCollection previousTraitCollection) -> void
 ~override Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRenderer.ViewWillTransitionToSize(CoreGraphics.CGSize toSize, UIKit.IUIViewControllerTransitionCoordinator coordinator) -> void

src/Controls/src/Core/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt

@@ -16,6 +16,7 @@ override Microsoft.Maui.Controls.Handlers.Items2.StructuredItemsViewController2<
 Microsoft.Maui.Controls.IndicatorView.~IndicatorView() -> void
 ~override Microsoft.Maui.Controls.SwipeItems.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Label.~Label() -> void
+Microsoft.Maui.Controls.SwipeView.~SwipeView() -> void
 override Microsoft.Maui.Controls.Handlers.Items.MauiCollectionView.LayoutSubviews() -> void
 ~override Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRenderer.TraitCollectionDidChange(UIKit.UITraitCollection previousTraitCollection) -> void
 ~override Microsoft.Maui.Controls.Platform.Compatibility.ShellSectionRenderer.ViewWillTransitionToSize(CoreGraphics.CGSize toSize, UIKit.IUIViewControllerTransitionCoordinator coordinator) -> void

src/Controls/src/Core/PublicAPI/net-tizen/PublicAPI.Unshipped.txt

@@ -6,3 +6,4 @@ override Microsoft.Maui.Controls.TitleBar.OnBindingContextChanged() -> void
 Microsoft.Maui.Controls.IndicatorView.~IndicatorView() -> void
 ~override Microsoft.Maui.Controls.SwipeItems.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Label.~Label() -> void
+Microsoft.Maui.Controls.SwipeView.~SwipeView() -> void

src/Controls/src/Core/PublicAPI/net-windows/PublicAPI.Unshipped.txt

@@ -8,3 +8,4 @@ Microsoft.Maui.Controls.IndicatorView.~IndicatorView() -> void
 override Microsoft.Maui.Controls.Handlers.Items.CarouselViewHandler.UpdateEmptyViewVisibility() -> void
 ~override Microsoft.Maui.Controls.SwipeItems.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Label.~Label() -> void
+Microsoft.Maui.Controls.SwipeView.~SwipeView() -> void

src/Controls/src/Core/PublicAPI/net/PublicAPI.Unshipped.txt

@@ -6,3 +6,4 @@ override Microsoft.Maui.Controls.TitleBar.OnBindingContextChanged() -> void
 Microsoft.Maui.Controls.IndicatorView.~IndicatorView() -> void
 ~override Microsoft.Maui.Controls.SwipeItems.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Label.~Label() -> void
+Microsoft.Maui.Controls.SwipeView.~SwipeView() -> void

src/Controls/src/Core/PublicAPI/netstandard/PublicAPI.Unshipped.txt

@@ -6,3 +6,4 @@ override Microsoft.Maui.Controls.TitleBar.OnBindingContextChanged() -> void
 Microsoft.Maui.Controls.IndicatorView.~IndicatorView() -> void
 ~override Microsoft.Maui.Controls.SwipeItems.OnPropertyChanged(string propertyName = null) -> void
 Microsoft.Maui.Controls.Label.~Label() -> void
+Microsoft.Maui.Controls.SwipeView.~SwipeView() -> void

src/Controls/src/Core/SwipeView/SwipeView.cs

@@ -237,6 +237,12 @@ public IPlatformElementConfiguration<T, SwipeView> On<T>() where T : IConfigPlat
 		View? _scrollParent;
 		Element? _templateParent;
 		SwipeDirection? _swipeDirection;
+		WeakScrollParentProxy? _scrolledProxy;
+
+		~SwipeView()
+		{
+			_scrolledProxy?.Unsubscribe();
+		}
 
 		ISwipeItems ISwipeView.LeftItems => new HandlerSwipeItems(LeftItems);
 
@@ -323,20 +329,7 @@ private protected override void OnParentChangedCore()
 
 		void UnsubscribeFromParentScrolledEvents()
 		{
-			if (_scrollParent is ScrollView scrollView)
-			{
-				scrollView.Scrolled -= OnParentScrolled;
-			}
-#pragma warning disable CS0618 // Type or member is obsolete
-			else if (_scrollParent is ListView listView)
-			{
-				listView.Scrolled -= OnParentScrolled;
-			}
-#pragma warning restore CS0618 // Type or member is obsolete
-			else if (_scrollParent is CollectionView collectionView)
-			{
-				collectionView.Scrolled -= OnParentScrolled;
-			}
+			_scrolledProxy?.Unsubscribe();
 			_scrollParent = null;
 		}
 
@@ -356,7 +349,7 @@ bool SubscribeToNearestScrollParent(Element startElement)
 
 			if (_scrollParent is ScrollView scrollView)
 			{
-				scrollView.Scrolled += OnParentScrolled;
+				EnsureScrolledProxy().Subscribe(this, scrollView);
 				return true;
 			}
 
@@ -365,7 +358,7 @@ bool SubscribeToNearestScrollParent(Element startElement)
 
 			if (_scrollParent is ListView listView)
 			{
-				listView.Scrolled += OnParentScrolled;
+				EnsureScrolledProxy().Subscribe(this, listView);
 				return true;
 			}
 #pragma warning restore CS0618 // Type or member is obsolete
@@ -374,13 +367,15 @@ bool SubscribeToNearestScrollParent(Element startElement)
 
 			if (_scrollParent is Microsoft.Maui.Controls.CollectionView collectionView)
 			{
-				collectionView.Scrolled += OnParentScrolled;
+				EnsureScrolledProxy().Subscribe(this, collectionView);
 				return true;
 			}
 
 			return false;
 		}
 
+		WeakScrollParentProxy EnsureScrolledProxy() => _scrolledProxy ??= new WeakScrollParentProxy();
+
 		void UpdateMargin()
 		{
 			if (this is not ISwipeView swipeView)
@@ -408,6 +403,75 @@ void OnParentScrolled(object? sender, ItemsViewScrolledEventArgs e)
 				((ISwipeView)this).RequestClose(new SwipeViewCloseRequest(true));
 		}
 
+		// Subscribes to an ancestor scroll container's Scrolled event via a WeakReference back to the
+		// SwipeView, so a long-lived scroll parent does not root a SwipeView that has been detached from
+		// the visual tree without its direct Parent changing (see issue #36481).
+		sealed class WeakScrollParentProxy
+		{
+			WeakReference<SwipeView>? _swipeView;
+			View? _source;
+
+			public void Subscribe(SwipeView swipeView, View source)
+			{
+				Unsubscribe();
+
+				_swipeView = new WeakReference<SwipeView>(swipeView);
+				_source = source;
+
+				switch (source)
+				{
+					case ScrollView scrollView:
+						scrollView.Scrolled += OnScrolled;
+						break;
+#pragma warning disable CS0618 // Type or member is obsolete
+					case ListView listView:
+						listView.Scrolled += OnScrolled;
+						break;
+#pragma warning restore CS0618 // Type or member is obsolete
+					case CollectionView collectionView:
+						collectionView.Scrolled += OnItemsViewScrolled;
+						break;
+				}
+			}
+
+			public void Unsubscribe()
+			{
+				switch (_source)
+				{
+					case ScrollView scrollView:
+						scrollView.Scrolled -= OnScrolled;
+						break;
+#pragma warning disable CS0618 // Type or member is obsolete
+					case ListView listView:
+						listView.Scrolled -= OnScrolled;
+						break;
+#pragma warning restore CS0618 // Type or member is obsolete
+					case CollectionView collectionView:
+						collectionView.Scrolled -= OnItemsViewScrolled;
+						break;
+				}
+
+				_source = null;
+				_swipeView = null;
+			}
+
+			void OnScrolled(object? sender, ScrolledEventArgs e)
+			{
+				if (_swipeView is not null && _swipeView.TryGetTarget(out var swipeView))
+					swipeView.OnParentScrolled(sender, e);
+				else
+					Unsubscribe();
+			}
+
+			void OnItemsViewScrolled(object? sender, ItemsViewScrolledEventArgs e)
+			{
+				if (_swipeView is not null && _swipeView.TryGetTarget(out var swipeView))
+					swipeView.OnParentScrolled(sender, e);
+				else
+					Unsubscribe();
+			}
+		}
+
 		void ISwipeView.SwipeStarted(SwipeViewSwipeStarted swipeStarted)
 		{
 			_swipeDirection = swipeStarted.SwipeDirection;

src/Controls/tests/Core.UnitTests/SwipeViewMemoryLeakTests.cs

@@ -0,0 +1,45 @@
+using System;
+using System.Threading.Tasks;
+using Xunit;
+
+namespace Microsoft.Maui.Controls.Core.UnitTests
+{
+	public class SwipeViewMemoryLeakTests : BaseTestFixture
+	{
+		/// <summary>
+		/// Verifies that a <see cref="SwipeView"/> placed beneath a long-lived <see cref="ScrollView"/>
+		/// does not leak after it is detached from the scroll container by removing an intermediate
+		/// ancestor (which leaves the SwipeView's direct parent unchanged). Reproduces issue #36481:
+		/// the ancestor <c>Scrolled</c> subscription was a plain (non-weak) delegate, so the long-lived
+		/// ScrollView permanently rooted the detached SwipeView and its subtree.
+		/// </summary>
+		[Fact, Category(TestCategory.Memory)]
+		public async Task SwipeViewDoesNotLeakWhenAncestorScrollViewOutlivesIt()
+		{
+			// The ScrollView is the long-lived root that outlives the SwipeView.
+			var scroll = new ScrollView();
+
+			WeakReference CreateSwipeViewReference()
+			{
+				var inner = new VerticalStackLayout();
+				scroll.Content = inner;
+
+				var swipe = new SwipeView { Content = new Label() };
+				inner.Children.Add(swipe);   // subscribes to scroll.Scrolled
+
+				// Detach the intermediate ancestor: swipe.Parent stays 'inner', so the
+				// direct-parent-change teardown never runs.
+				scroll.Content = null;
+
+				return new WeakReference(swipe);
+			}
+
+			var reference = CreateSwipeViewReference();
+
+			Assert.False(await reference.WaitForCollect(), "SwipeView should not be alive!");
+
+			// Keep the long-lived ScrollView alive for the duration of the test.
+			GC.KeepAlive(scroll);
+		}
+	}
+}