[iOS] Fix Switch custom colors on iOS 26

src/Controls/tests/TestCases.HostApp/MauiProgram.cs

@@ -89,7 +89,7 @@ public static Page CreateDefaultMainPage()
 		{
 			Page mainPage = null;
 			OverrideMainPage(ref mainPage);
-#if MACCATALYST
+#if IOS || MACCATALYST
 			// Check for startup test argument from environment variables (passed by test runner)
 			var testName = System.Environment.GetEnvironmentVariable("test");
 

src/Core/src/Handlers/Switch/SwitchHandler.iOS.cs

@@ -1,10 +1,8 @@
 using System;
-using System.Threading.Tasks;
 using CoreFoundation;
 using Foundation;
 using Microsoft.Maui.Graphics;
 using Microsoft.Maui.Platform;
-using ObjCRuntime;
 using UIKit;
 using RectangleF = CoreGraphics.CGRect;
 
@@ -22,7 +20,7 @@ public partial class SwitchHandler : ViewHandler<ISwitch, UISwitch>
 
 		protected override UISwitch CreatePlatformView()
 		{
-			return new UISwitch(RectangleF.Empty);
+			return new MauiSwitch(RectangleF.Empty);
 		}
 
 		protected override void ConnectHandler(UISwitch platformView)
@@ -70,12 +68,12 @@ class SwitchProxy
 
 			NSObject? _willEnterForegroundObserver;
 			NSObject? _windowDidBecomeKeyObserver;
-			IUITraitChangeRegistration? _traitChangeRegistration;
 
 			public void Connect(ISwitch virtualView, UISwitch platformView)
 			{
 				_virtualView = new(virtualView);
 				_platformView = new(platformView);
+				(platformView as MauiSwitch)?.Connect(virtualView);
 				platformView.ValueChanged += OnControlValueChanged;
 
 #if MACCATALYST
@@ -102,25 +100,10 @@ public void Connect(ISwitch virtualView, UISwitch platformView)
 					});
 #endif
 
-				// iOS/MacCatalyst 26+ resets ThumbTintColor when theme changes (light/dark mode).
-				// Register for trait changes to re-apply ThumbColor after UIKit completes its styling.
+				// iOS/MacCatalyst 26+ can reset custom switch colors during initial UIKit styling.
+				// Re-apply after connect; MauiSwitch handles later trait/layout/window reapply paths.
 				if (OperatingSystem.IsIOSVersionAtLeast(26) || OperatingSystem.IsMacCatalystVersionAtLeast(26))
 				{
-					if (_traitChangeRegistration is not null)
-					{
-						platformView.UnregisterForTraitChanges(_traitChangeRegistration);
-					}
-
-					_traitChangeRegistration = platformView.RegisterForTraitChanges<UITraitUserInterfaceStyle>(
-						(IUITraitEnvironment view, UITraitCollection _) =>
-						{
-							if (view is UISwitch uiSwitch)
-							{
-								UpdateThumbAndTrackColor(uiSwitch);
-							}
-						});
-
-					// iOS 26+ resets ThumbTintColor after initial layout, so re-apply the custom ThumbColor here.
 					UpdateThumbAndTrackColor(platformView);
 				}
 			}
@@ -130,48 +113,33 @@ public void Connect(ISwitch virtualView, UISwitch platformView)
 			// especially when the app enters the background and returns to the foreground.
 			void UpdateTrackOffColor(UISwitch platformView)
 			{
-				DispatchQueue.MainQueue.DispatchAsync(async () =>
+				DispatchQueue.MainQueue.DispatchAsync(() =>
 				{
-					if (!platformView.On)
+					if (!platformView.On && VirtualView is ISwitch view && view.TrackColor is not null)
 					{
-						await Task.Delay(10); // Small delay, necessary to allow UIKit to complete its internal layout and styling processes before re-applying the custom color
-
-						if (VirtualView is ISwitch view && view.TrackColor is not null)
-						{
-							platformView.UpdateTrackColor(view);
-						}
+						platformView.UpdateTrackColor(view);
+						(platformView as MauiSwitch)?.SetNeedsColorReapply();
 					}
 				});
 			}
 
 			void UpdateThumbAndTrackColor(UISwitch platformView)
 			{
-				DispatchQueue.MainQueue.DispatchAsync(async () =>
+				DispatchQueue.MainQueue.DispatchAsync(() =>
 				{
-					if (VirtualView is null || PlatformView is null)
+					if (VirtualView is not ISwitch view || PlatformView is null || !view.HasCustomColors())
 						return;
 
-					await Task.Delay(10); // Small delay, necessary to allow UIKit to complete its internal layout and styling processes before re-applying the custom color
-
-					if (VirtualView is ISwitch view)
-					{
-						// iOS 26+ "Liquid Glass" resets TrackColor during post-connect layout. Re-apply both.
-						if (view.TrackColor is not null)
-						{
-							platformView.UpdateTrackColor(view);
-						}
-
-						if (view.ThumbColor is not null)
-						{
-							platformView.UpdateThumbColor(view);
-						}
-					}
+					platformView.UpdateTrackColor(view);
+					platformView.UpdateThumbColor(view);
+					(platformView as MauiSwitch)?.SetNeedsColorReapply();
 				});
 			}
 
 			public void Disconnect(UISwitch platformView)
 			{
 				platformView.ValueChanged -= OnControlValueChanged;
+				(platformView as MauiSwitch)?.Disconnect();
 
 				if (_willEnterForegroundObserver is not null)
 				{
@@ -183,11 +151,6 @@ public void Disconnect(UISwitch platformView)
 					NSNotificationCenter.DefaultCenter.RemoveObserver(_windowDidBecomeKeyObserver);
 					_windowDidBecomeKeyObserver = null;
 				}
-				if (_traitChangeRegistration is not null)
-				{
-					platformView.UnregisterForTraitChanges(_traitChangeRegistration);
-					_traitChangeRegistration = null;
-				}
 			}
 
 			void OnControlValueChanged(object? sender, EventArgs e)
@@ -199,4 +162,4 @@ void OnControlValueChanged(object? sender, EventArgs e)
 			}
 		}
 	}
-}
+}

src/Core/src/Platform/iOS/MauiSwitch.cs

@@ -0,0 +1,133 @@
+using System;
+using CoreFoundation;
+using CoreGraphics;
+using UIKit;
+
+namespace Microsoft.Maui.Platform
+{
+	internal class MauiSwitch : UISwitch
+	{
+		WeakReference<ISwitch>? _virtualView;
+		bool _colorReapplyQueued;
+		bool _isReapplyingColors;
+		bool _needsColorReapply;
+		bool _hasMauiTrackColorOverride;
+
+		public MauiSwitch(CGRect frame) : base(frame)
+		{
+		}
+
+		public void Connect(ISwitch virtualView)
+		{
+			_virtualView = new(virtualView);
+			SetNeedsColorReapply();
+		}
+
+		public void Disconnect()
+		{
+			_virtualView = null;
+			_needsColorReapply = false;
+		}
+
+		public void SetNeedsColorReapply()
+		{
+			var virtualView = VirtualView;
+
+			if (virtualView is null || virtualView.ShouldPreserveNativeDefaults())
+			{
+				_needsColorReapply = false;
+				return;
+			}
+
+			_needsColorReapply = true;
+			SetNeedsLayout();
+			QueueColorReapply();
+		}
+
+		public override void MovedToWindow()
+		{
+			base.MovedToWindow();
+			if (Window is not null)
+			{
+				SetNeedsColorReapply();
+			}
+		}
+
+		public override void LayoutSubviews()
+		{
+			base.LayoutSubviews();
+			QueueColorReapply();
+		}
+
+		public override void TraitCollectionDidChange(UITraitCollection? previousTraitCollection)
+		{
+			base.TraitCollectionDidChange(previousTraitCollection);
+			SetNeedsColorReapply();
+		}
+
+		void QueueColorReapply()
+		{
+			if (_colorReapplyQueued || !_needsColorReapply)
+			{
+				return;
+			}
+
+			_colorReapplyQueued = true;
+
+			DispatchQueue.MainQueue.DispatchAsync(() =>
+			{
+				_colorReapplyQueued = false;
+				TryReapplyColors();
+			});
+		}
+
+		void TryReapplyColors()
+		{
+			if (_isReapplyingColors || !_needsColorReapply)
+			{
+				return;
+			}
+
+			var virtualView = VirtualView;
+
+			if (virtualView is null || virtualView.ShouldPreserveNativeDefaults())
+			{
+				_needsColorReapply = false;
+				return;
+			}
+
+			if (!this.IsReadyForColorReapply())
+			{
+				return;
+			}
+
+			_isReapplyingColors = true;
+
+			try
+			{
+				this.ApplyTrackColor(virtualView);
+				this.ApplyThumbColor(virtualView);
+				_needsColorReapply = false;
+			}
+			finally
+			{
+				_isReapplyingColors = false;
+			}
+		}
+
+		ISwitch? VirtualView =>
+			_virtualView is not null && _virtualView.TryGetTarget(out var virtualView) ? virtualView : null;
+
+		internal bool HasMauiTrackColorOverride => _hasMauiTrackColorOverride;
+
+		internal void MarkMauiTrackColorOverride()
+		{
+			_hasMauiTrackColorOverride = true;
+		}
+
+		internal void ClearMauiTrackColorOverride()
+		{
+			_hasMauiTrackColorOverride = false;
+		}
+	}
+}