[net7.0] [iOS] RadioButton a11y (#11969)

* First attempt of radiobutton a11y

* Make Switch trait work as expected

* Update control gallery sample

* Make class internal for potential backport

* Update based on feedback

* Add comment

* Update based on feedback

* Refactor based on feedback

* Update

* Update

Co-authored-by: Rachel Kang <rachelkang@microsoft.com>

src/Controls/samples/Controls.Sample/Pages/Controls/RadioButtonGalleries/ContentProperties.xaml

@@ -43,6 +43,39 @@
 
             </RadioButton>
 
+            <Label FontSize="Small" Text="The RadioButton below is the same as above, but also has a Semantic Description set on it for better accessibility."/>
+
+            <RadioButton GroupName="test"
+                         SemanticProperties.Description="{Binding Source={x:Reference embeddedButton1}, Path=Text}"
+                         TextColor="Green"
+                         TextTransform="Uppercase"
+                         FontAttributes="Bold"
+                         FontSize="12"
+                         FontFamily="Arial">
+
+                <RadioButton.Content>
+                    <Button x:Name="embeddedButton1" Text="It's a button inside a button." TextColor="Green"></Button>
+                </RadioButton.Content>
+
+            </RadioButton>
+
+            <Label FontSize="Small" Text="The RadioButton below is the same as above, but  has a Semantic Description and Semantic Hint set on it for better accessibility."/>
+
+            <RadioButton GroupName="test"
+                         SemanticProperties.Description="{Binding Source={x:Reference embeddedButton2}, Path=Text}"
+                         SemanticProperties.Hint="Tests semantics on a radio button with a button set as its content"
+                         TextColor="Green"
+                         TextTransform="Uppercase"
+                         FontAttributes="Bold"
+                         FontSize="12"
+                         FontFamily="Arial">
+
+                <RadioButton.Content>
+                    <Button x:Name="embeddedButton2" Text="It's a button inside a button." TextColor="Green"></Button>
+                </RadioButton.Content>
+
+            </RadioButton>
+
             <Label FontSize="Small" Text="A Content View which already has these properties set/bound should ignore the RadioButton properties."/>
 
             <RadioButton GroupName="test" 

src/Controls/samples/Controls.Sample/Pages/Controls/RadioButtonGalleries/RadioButtonGroupGalleryPage.xaml

@@ -117,7 +117,12 @@
                         </x:Array>
                     </ListView.ItemsSource>
                 </ListView>
-            </StackLayout>
+                <Label FontSize="Small" Text="RadioButton with a Semantic Description and Semantic Hint"/>
+                <RadioButton
+                    Content="RadioButton, Group=null"
+                    SemanticProperties.Description="Semantic description"
+                    SemanticProperties.Hint="Semantic hint" />
+                </StackLayout>
         </ScrollView>
     </ContentPage>
 

src/Controls/src/Core/HandlerImpl/RadioButton/RadioButton.Impl.cs

@@ -19,5 +19,23 @@ public partial class RadioButton : IRadioButton
 		Color IButtonStroke.StrokeColor => (Color)GetValue(BorderColorProperty);
 
 		int IButtonStroke.CornerRadius => (int)GetValue(CornerRadiusProperty);
+
+		private protected override Semantics UpdateSemantics()
+		{
+			var semantics = base.UpdateSemantics();
+
+			if (ControlTemplate != null)
+			{
+				string contentAsString = ContentAsString();
+
+				if (!string.IsNullOrWhiteSpace(contentAsString) && string.IsNullOrWhiteSpace(semantics?.Description))
+				{
+					semantics ??= new Semantics();
+					semantics.Description = contentAsString;
+				}
+			}
+
+			return semantics;
+		}
 	}
 }

src/Controls/src/Core/HandlerImpl/VisualElement/VisualElement.Impl.cs

@@ -9,7 +9,7 @@ namespace Microsoft.Maui.Controls
 	/// <include file="../../../../docs/Microsoft.Maui.Controls/VisualElement.xml" path="Type[@FullName='Microsoft.Maui.Controls.VisualElement']/Docs/*" />
 	public partial class VisualElement : IView
 	{
-		Semantics _semantics;
+		Semantics? _semantics;
 		bool _isLoadedFired;
 		EventHandler? _loaded;
 		EventHandler? _unloaded;
@@ -163,28 +163,23 @@ bool IView.IsFocused
 
 		Visibility IView.Visibility => IsVisible.ToVisibility();
 
-		Semantics IView.Semantics
-		{
-			get
-			{
-				UpdateSemantics();
-				return _semantics;
-			}
-		}
+		Semantics? IView.Semantics => UpdateSemantics();
 
-		void UpdateSemantics()
+		private protected virtual Semantics? UpdateSemantics()
 		{
 			if (!this.IsSet(SemanticProperties.HintProperty) &&
 				!this.IsSet(SemanticProperties.DescriptionProperty) &&
 				!this.IsSet(SemanticProperties.HeadingLevelProperty))
 			{
-				return;
+				_semantics = null;
+				return _semantics;
 			}
 
 			_semantics ??= new Semantics();
 			_semantics.Description = SemanticProperties.GetDescription(this);
 			_semantics.HeadingLevel = SemanticProperties.GetHeadingLevel(this);
 			_semantics.Hint = SemanticProperties.GetHint(this);
+			return _semantics;
 		}
 
 		static double EnsurePositive(double value)

src/Core/src/Handlers/RadioButton/RadioButtonHandler.iOS.cs

@@ -9,11 +9,7 @@ protected override ContentView CreatePlatformView()
 			_ = VirtualView ?? throw new InvalidOperationException($"{nameof(VirtualView)} must be set to create a {nameof(ContentView)}");
 			_ = MauiContext ?? throw new InvalidOperationException($"{nameof(MauiContext)} cannot be null");
 
-			return new ContentView
-			{
-				CrossPlatformMeasure = VirtualView.CrossPlatformMeasure,
-				CrossPlatformArrange = VirtualView.CrossPlatformArrange
-			};
+			return new SemanticSwitchContentView(VirtualView);
 		}
 
 		public override void SetVirtualView(IView view)
@@ -45,8 +41,13 @@ public static void MapContent(IRadioButtonHandler handler, IContentView page)
 			UpdateContent(handler);
 		}
 
-		[MissingMapper]
-		public static void MapIsChecked(IRadioButtonHandler handler, IRadioButton radioButton) { }
+		public static void MapIsChecked(IRadioButtonHandler handler, IRadioButton radioButton)
+		{
+			if (radioButton.IsChecked)
+				handler.PlatformView.AccessibilityValue = "1";
+			else
+				handler.PlatformView.AccessibilityValue = "0";
+		}
 
 		[MissingMapper]
 		public static void MapTextColor(IRadioButtonHandler handler, ITextStyle textStyle) { }

src/Core/src/Platform/iOS/SemanticSwitchContentView.cs

@@ -0,0 +1,42 @@
+using System;
+using CoreGraphics;
+using Microsoft.Maui.Graphics;
+using ObjCRuntime;
+using UIKit;
+
+namespace Microsoft.Maui.Platform;
+
+// This class should remain internal until further refactored.
+// It is currently being used only for RadioButton accessibility on iOS.
+internal class SemanticSwitchContentView : ContentView
+{
+	UIAccessibilityTrait _accessibilityTraits;
+
+	internal SemanticSwitchContentView(IContentView virtualView)
+	{
+		CrossPlatformMeasure = virtualView.CrossPlatformMeasure;
+		CrossPlatformArrange = virtualView.CrossPlatformArrange;
+		IsAccessibilityElement = true;
+	}
+
+	static UIKit.UIAccessibilityTrait? s_switchAccessibilityTraits;
+	UIKit.UIAccessibilityTrait SwitchAccessibilityTraits
+	{
+		get
+		{
+			if (s_switchAccessibilityTraits == null ||
+				s_switchAccessibilityTraits == UIKit.UIAccessibilityTrait.None)
+			{
+				s_switchAccessibilityTraits = new UIKit.UISwitch().AccessibilityTraits;
+			}
+
+			return s_switchAccessibilityTraits ?? UIKit.UIAccessibilityTrait.None;
+		}
+	}
+
+	public override UIAccessibilityTrait AccessibilityTraits
+	{
+		get => _accessibilityTraits |= SwitchAccessibilityTraits;
+		set => _accessibilityTraits = value | SwitchAccessibilityTraits;
+	}
+}