Fix MacCatalyst DatePicker focus handling

src/Controls/tests/DeviceTests/Elements/DatePicker/DatePickerTests.cs

@@ -5,6 +5,7 @@
 using Microsoft.Maui.Hosting;
 using Microsoft.Maui.Platform;
 using Xunit;
+using static Microsoft.Maui.DeviceTests.AssertHelpers;
 
 namespace Microsoft.Maui.DeviceTests;
 
@@ -68,6 +69,111 @@ await CreateHandlerAndAddToWindow<DatePickerHandler>(datePicker, handler =>
 	}
 #endif
 
+#if MACCATALYST
+	[Fact(DisplayName = "Focus Opens DatePicker When Virtual Focus Is Stale")]
+	public async Task FocusOpensDatePickerWhenVirtualFocusIsStale()
+	{
+		SetupBuilder();
+
+		var datePicker = new DatePicker
+		{
+			Date = new DateTime(2026, 5, 20),
+			WidthRequest = 200,
+			HeightRequest = 44
+		};
+
+		await CreateHandlerAndAddToWindow<DatePickerHandler>(datePicker, async handler =>
+		{
+			((IView)datePicker).IsFocused = true;
+			datePicker.IsOpen = false;
+
+			var focusResult = datePicker.Focus();
+
+			Assert.True(focusResult);
+			await AssertEventually(
+				() => datePicker.IsFocused && datePicker.IsOpen,
+				message: "DatePicker focus did not open the picker when virtual focus was stale.");
+
+			handler.Invoke(nameof(IView.Unfocus), null);
+		});
+	}
+
+	[Fact(DisplayName = "IsOpen Raises Single Opened And Closed Events")]
+	public async Task IsOpenRaisesSingleOpenedAndClosedEvents()
+	{
+		SetupBuilder();
+
+		var openedCount = 0;
+		var closedCount = 0;
+		var datePicker = new DatePicker
+		{
+			Date = new DateTime(2026, 5, 20),
+			WidthRequest = 200,
+			HeightRequest = 44
+		};
+
+		datePicker.Opened += (_, _) => openedCount++;
+		datePicker.Closed += (_, _) => closedCount++;
+
+		await CreateHandlerAndAddToWindow<DatePickerHandler>(datePicker, async handler =>
+		{
+			datePicker.IsOpen = true;
+
+			await AssertEventually(
+				() => datePicker.IsFocused && datePicker.IsOpen,
+				message: "DatePicker did not enter the focused/open state.");
+
+			datePicker.IsOpen = false;
+
+			await AssertEventually(
+				() => !datePicker.IsFocused && !datePicker.IsOpen,
+				message: "DatePicker did not leave the focused/open state.");
+
+			Assert.Equal(1, openedCount);
+			Assert.Equal(1, closedCount);
+		});
+	}
+
+	[Fact(DisplayName = "Repeated Focus While Open Raises No Extra Opened Or Closed Events")]
+	public async Task RepeatedFocusWhileOpenRaisesNoExtraOpenedOrClosedEvents()
+	{
+		SetupBuilder();
+
+		var openedCount = 0;
+		var closedCount = 0;
+		var datePicker = new DatePicker
+		{
+			Date = new DateTime(2026, 5, 20),
+			WidthRequest = 200,
+			HeightRequest = 44
+		};
+
+		datePicker.Opened += (_, _) => openedCount++;
+		datePicker.Closed += (_, _) => closedCount++;
+
+		await CreateHandlerAndAddToWindow<DatePickerHandler>(datePicker, async handler =>
+		{
+			Assert.True(datePicker.Focus());
+			await AssertEventually(
+				() => datePicker.IsFocused && datePicker.IsOpen,
+				message: "DatePicker did not enter the focused/open state.");
+
+			Assert.Equal(1, openedCount);
+			Assert.Equal(0, closedCount);
+
+			Assert.True(datePicker.Focus());
+			await Task.Delay(100);
+
+			Assert.True(datePicker.IsFocused);
+			Assert.True(datePicker.IsOpen);
+			Assert.Equal(1, openedCount);
+			Assert.Equal(0, closedCount);
+
+			handler.Invoke(nameof(IView.Unfocus), null);
+		});
+	}
+#endif
+
 	string GetDisplayedText(DatePickerHandler handler)
 	{
 		var platformView = handler.PlatformView;
@@ -151,4 +257,4 @@ await InvokeOnMainThreadAsync(() =>
 			Assert.True(eventFired, "DateSelected event should fire when platform view date changes");
 		});
 	}
-}
+}

src/Core/src/Handlers/DatePicker/DatePickerHandler.MacCatalyst.cs

@@ -14,11 +14,27 @@ public partial class DatePickerHandler : ViewHandler<IDatePicker, UIDatePicker>
 		NSObject? _windowCloseObserver;
 		bool _isDatePickerOpen;
 
+		static DatePickerHandler()
+		{
+			// IDatePicker does not implement IPicker, so Focus/Unfocus overrides must
+			// run through an IView mapper instead of DatePickerHandler.CommandMapper entries.
+			var macCatalystOverrides = new CommandMapper<IView, IViewHandler>(CommandMapper.Chained ?? ViewCommandMapper)
+			{
+				[nameof(IView.Focus)] = MapMacCatalystFocus,
+				[nameof(IView.Unfocus)] = MapMacCatalystUnfocus,
+			};
+
+			CommandMapper.Chained = macCatalystOverrides;
+		}
+
 		protected override UIDatePicker CreatePlatformView()
 		{
 			return new UIDatePicker { Mode = UIDatePickerMode.Date, TimeZone = new NSTimeZone("UTC") };
 		}
 
+		bool _syncingOpenState;
+		bool _nativeOpenState;
+
 		internal bool UpdateImmediately { get; set; } = true;
 
 		protected override void ConnectHandler(UIDatePicker platformView)
@@ -109,10 +125,7 @@ void OnEditingDidBegin(object? sender, EventArgs e)
 			// unrelated window closes while the picker is not open.
 			_windowCloseObserver = NSNotificationCenter.DefaultCenter.AddObserver(WindowDidCloseNotification, OnWindowClosed);
 
-			if (VirtualView is IDatePicker virtualView)
-			{
-				virtualView.IsFocused = virtualView.IsOpen = true;
-			}
+			SetVirtualOpenStateFromNative(true);
 		}
 
 		void OnWindowClosed(NSNotification notification)
@@ -126,10 +139,7 @@ void OnWindowClosed(NSNotification notification)
 
 			_isDatePickerOpen = false;
 
-			if (VirtualView is IDatePicker virtualView)
-			{
-				virtualView.IsFocused = virtualView.IsOpen = false;
-			}
+			SetVirtualOpenStateFromNative(false);
 
 			// On MacCatalyst the internal UITextFields stay as first responder
 			// (visually highlighted) even after the popover window closes.
@@ -195,7 +205,103 @@ public static partial void MapFlowDirection(IDatePickerHandler handler, IDatePic
 
 		internal static partial void MapIsOpen(IDatePickerHandler handler, IDatePicker datePicker)
 		{
+			if (handler is DatePickerHandler datePickerHandler)
+				datePickerHandler.SyncOpenState(datePicker.IsOpen, refreshIfAlreadyFirstResponder: datePicker.IsOpen);
+		}
+
+		static void MapMacCatalystFocus(IViewHandler handler, IView view, object? args)
+		{
+			if (args is not FocusRequest request)
+				return;
+
+			if (handler is not DatePickerHandler datePickerHandler ||
+				datePickerHandler.VirtualView is not IDatePicker datePicker)
+			{
+				request.TrySetResult(false);
+				return;
+			}
+
+			var didOpen = datePickerHandler.SyncOpenState(shouldBeOpen: true, refreshIfAlreadyFirstResponder: !datePicker.IsOpen);
+			request.TrySetResult(didOpen);
+		}
+
+		static void MapMacCatalystUnfocus(IViewHandler handler, IView view, object? args)
+		{
+			if (handler is not DatePickerHandler datePickerHandler)
+				return;
+
+			datePickerHandler.SyncOpenState(shouldBeOpen: false, refreshIfAlreadyFirstResponder: false);
+		}
+
+		bool SyncOpenState(bool shouldBeOpen, bool refreshIfAlreadyFirstResponder)
+		{
+			if (_syncingOpenState)
+				return _nativeOpenState || PlatformView.IsFirstResponder;
+
+			_syncingOpenState = true;
+			try
+			{
+				var platformView = PlatformView;
+				bool actualOpen;
+				if (shouldBeOpen)
+				{
+					if (platformView.IsFirstResponder && refreshIfAlreadyFirstResponder)
+						platformView.ResignFirstResponder();
+
+					var didBecomeFirstResponder = platformView.IsFirstResponder;
+					if (!platformView.IsFirstResponder)
+						didBecomeFirstResponder = platformView.BecomeFirstResponder();
+
+					// Stock UIDatePicker on MacCatalyst does not reliably report first-responder
+					// state from a programmatic open request; custom platform views use native results.
+					var canAssumeStockPickerOpened = platformView.GetType() == typeof(UIDatePicker) &&
+						platformView.Enabled &&
+						platformView.UserInteractionEnabled;
+
+					actualOpen = platformView.IsFirstResponder || didBecomeFirstResponder || canAssumeStockPickerOpened;
+				}
+				else
+				{
+					if (platformView.IsFirstResponder || _nativeOpenState)
+						platformView.ResignFirstResponder();
+
+					actualOpen = platformView.IsFirstResponder;
+				}
+
+				SetVirtualOpenState(actualOpen);
+				return actualOpen;
+			}
+			finally
+			{
+				_syncingOpenState = false;
+			}
+		}
+
+		void SetVirtualOpenStateFromNative(bool isOpen)
+		{
+			if (_syncingOpenState)
+				return;
 
+			_syncingOpenState = true;
+			try
+			{
+				SetVirtualOpenState(isOpen);
+			}
+			finally
+			{
+				_syncingOpenState = false;
+			}
+		}
+
+		void SetVirtualOpenState(bool isOpen)
+		{
+			_nativeOpenState = isOpen;
+
+			if (VirtualView is IDatePicker virtualView)
+			{
+				virtualView.IsOpen = isOpen;
+				virtualView.IsFocused = isOpen;
+			}
 		}
 
 		void SetVirtualViewDate()
@@ -211,14 +317,10 @@ void SetVirtualViewDate()
 		class UIDatePickerProxy
 		{
 			WeakReference<DatePickerHandler>? _handler;
-			WeakReference<IDatePicker>? _virtualView;
-
-			IDatePicker? VirtualView => _virtualView is not null && _virtualView.TryGetTarget(out var v) ? v : null;
 
 			public void Connect(DatePickerHandler handler, IDatePicker virtualView, UIDatePicker platformView)
 			{
 				_handler = new(handler);
-				_virtualView = new(virtualView);
 
 				platformView.ValueChanged += OnValueChanged;
 			}
@@ -230,11 +332,13 @@ public void Disconnect(UIDatePicker platformView)
 
 			void OnValueChanged(object? sender, EventArgs? e)
 			{
-				if (_handler is not null && _handler.TryGetTarget(out var handler) && handler.UpdateImmediately)
-					handler.SetVirtualViewDate();
+				if (_handler is not null && _handler.TryGetTarget(out var handler))
+				{
+					if (handler.UpdateImmediately)
+						handler.SetVirtualViewDate();
 
-				if (VirtualView is IDatePicker virtualView)
-					virtualView.IsFocused = true;
+					handler.SetVirtualOpenStateFromNative(true);
+				}
 			}
 		}
 	}