fix(TextBox): [iOS] Add temporary workaround for iOS 16 on selection …

…with UITextField

This change is needed to make the SinglelineTextBoxView.SelectedTextRange conditional, and avoid changing the value provided to UIKit. This breaks the use of `TextBoxSelectionChanged`, but can be restored by using the `FeatureConfiguration.TextBox.IOS16EnableSelectionSupport` feature flag if the issue ends up being fixed in UIKit. See #9430 for more details.

src/Uno.UI/FeatureConfiguration.cs

@@ -369,11 +369,21 @@ public static class TextBlock
 
 		public static class TextBox
 		{
+
 			/// <summary>
 			/// Determines if the caret is visible or not.
 			/// </summary>
 			/// <remarks>This feature is used to avoid screenshot comparisons false positives</remarks>
 			public static bool HideCaret { get; set; } = false;
+
+#if __IOS__
+			/// <summary>
+			/// As of iOS 16 Beta 4, the selection events are crashing the application. This feature configuration is added
+			/// to provide the ability to restore the original behavior if/when the underlying UIKit is fixed.
+			/// See https://github.com/unoplatform/uno/issues/9430 for additional details.
+			/// </summary>
+			public static bool IOS16EnableSelectionSupport { get; set; }
+#endif
 		}
 
 		public static class ScrollViewer

src/Uno.UI/UI/Xaml/Controls/TextBox/SinglelineTextBoxView.iOS.cs

@@ -10,6 +10,10 @@
 using Uno.UI.Controls;
 using Windows.UI;
 using Uno.Disposables;
+using Foundation;
+using Uno.Foundation.Logging;
+using Uno.UI;
+using static Uno.UI.FeatureConfiguration;
 
 namespace Windows.UI.Xaml.Controls
 {
@@ -19,6 +23,8 @@ public partial class SinglelineTextBoxView : UITextField, ITextBoxView, Dependen
 		private readonly WeakReference<TextBox> _textBox;
 		private readonly SerialDisposable _foregroundChanged = new SerialDisposable();
 
+		private static bool _issue9430WarnSingle = false;
+
 		public SinglelineTextBoxView(TextBox textBox)
 		{
 			_textBox = new WeakReference<TextBox>(textBox);
@@ -27,6 +33,26 @@ public SinglelineTextBoxView(TextBox textBox)
 			Initialize();
 		}
 
+		internal static SinglelineTextBoxView CreateSinglelineTextBoxView(TextBox textBox)
+		{
+			if (UIDevice.CurrentDevice.CheckSystemVersion(16, 0) && !FeatureConfiguration.TextBox.IOS16EnableSelectionSupport)
+			{
+				if (!_issue9430WarnSingle && typeof(SinglelineTextBoxView).Log().IsEnabled(LogLevel.Error))
+				{
+					_issue9430WarnSingle = true;
+					typeof(SinglelineTextBoxView).Log().Error($"TextBox selection events are disabled on iOS 16. See https://github.com/unoplatform/uno/issues/9430 for additional details.");
+				}
+
+				return new SinglelineTextBoxView(textBox);
+			}
+			else
+			{
+				return new SinglelineTextBoxViewWithSelection(textBox);
+			}
+		}
+
+		internal TextBox TextBox => _textBox.GetTarget();
+
 		private void OnEditingChanged(object sender, EventArgs e)
 		{
 			OnTextChanged();
@@ -198,6 +224,17 @@ public void RefreshFont()
 		{
 			UpdateFont();
 		}
+	}
+
+	/// <summary>
+	/// Workaround for https://github.com/unoplatform/uno/issues/9430
+	/// </summary>
+	internal partial class SinglelineTextBoxViewWithSelection : SinglelineTextBoxView
+	{
+		public SinglelineTextBoxViewWithSelection(TextBox textBox)
+			: base(textBox)
+		{
+		}
 
 		public override UITextRange SelectedTextRange
 		{
@@ -207,7 +244,7 @@ public override UITextRange SelectedTextRange
 			}
 			set
 			{
-				var textBox = _textBox.GetTarget();
+				var textBox = TextBox;
 
 				if (textBox != null && base.SelectedTextRange != value)
 				{

src/Uno.UI/UI/Xaml/Controls/TextBox/TextBox.iOS.cs

@@ -103,7 +103,7 @@ private void UpdateTextBoxView()
 						return;
 					}
 
-					_textBoxView = new SinglelineTextBoxView(this);
+					_textBoxView = SinglelineTextBoxView.CreateSinglelineTextBoxView(this);
 
 					_contentElement.Content = _textBoxView;
 					_textBoxView.SetTextNative(Text);