fix: ios PasswordBox changed event when focus

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

@@ -29,7 +29,7 @@ public override bool ShouldChangeCharacters(UITextField textField, NSRange range
 		{
 			if (textField is SinglelineTextBoxView textBoxView)
 			{
-				if (_textBox.GetTarget() is not TextBox textBox)
+				if (_textBox.GetTarget() is not { } textBox)
 				{
 					return false;
 				}
@@ -50,7 +50,7 @@ public override bool ShouldChangeCharacters(UITextField textField, NSRange range
 					// When replacing text from pasting (multiple characters at once)
 					// we should only allow it (return true) when the new text length
 					// is lower or equal to the allowed length (TextBox.MaxLength)
-					var newLength = textBoxView.Text.Length + replacementString.Length - range.Length;
+					var newLength = textBoxView.Text?.Length + replacementString.Length - range.Length;
 					return newLength <= textBox.MaxLength;
 				};
 			}

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

@@ -1,4 +1,5 @@
-using System;
+#nullable enable
+using System;
 using System.Runtime.InteropServices;
 using CoreGraphics;
 using Foundation;
@@ -19,10 +20,10 @@ namespace Microsoft.UI.Xaml.Controls
 {
 	public partial class SinglelineTextBoxView : UITextField, ITextBoxView, DependencyObject, IFontScalable
 	{
-		private SinglelineTextBoxDelegate _delegate;
+		private SinglelineTextBoxDelegate _delegate = null!;
 		private readonly WeakReference<TextBox> _textBox;
-		private Action _foregroundChanged;
-		private IDisposable _foregroundBrushChangedSubscription;
+		private Action? _foregroundChanged;
+		private IDisposable? _foregroundBrushChangedSubscription;
 
 		public SinglelineTextBoxView(TextBox textBox)
 		{
@@ -32,13 +33,13 @@ public SinglelineTextBoxView(TextBox textBox)
 			Initialize();
 		}
 
-		public override void Paste(NSObject sender) => HandlePaste(() => base.Paste(sender));
+		public override void Paste(NSObject? sender) => HandlePaste(() => base.Paste(sender));
 
-		public override void PasteAndGo(NSObject sender) => HandlePaste(() => base.PasteAndGo(sender));
+		public override void PasteAndGo(NSObject? sender) => HandlePaste(() => base.PasteAndGo(sender));
 
-		public override void PasteAndMatchStyle(NSObject sender) => HandlePaste(() => base.PasteAndMatchStyle(sender));
+		public override void PasteAndMatchStyle(NSObject? sender) => HandlePaste(() => base.PasteAndMatchStyle(sender));
 
-		public override void PasteAndSearch(NSObject sender) => HandlePaste(() => base.PasteAndSearch(sender));
+		public override void PasteAndSearch(NSObject? sender) => HandlePaste(() => base.PasteAndSearch(sender));
 
 		public override void Paste(NSItemProvider[] itemProviders) => HandlePaste(() => base.Paste(itemProviders));
 
@@ -54,7 +55,7 @@ private void HandlePaste(Action baseAction)
 
 		internal TextBox TextBox => _textBox.GetTarget();
 
-		public override string Text
+		public override string? Text
 		{
 			get => base.Text;
 			set
@@ -69,15 +70,14 @@ public override string Text
 			}
 		}
 
-		private void OnEditingChanged(object sender, EventArgs e)
+		private void OnEditingChanged(object? sender, EventArgs e)
 		{
 			OnTextChanged();
 		}
 
 		private void OnTextChanged()
 		{
-			var textBox = _textBox?.GetTarget();
-			if (textBox != null)
+			if (TextBox is { } textBox)
 			{
 				var text = textBox.ProcessTextInput(Text);
 				SetTextNative(text);
@@ -99,29 +99,40 @@ private void Initialize()
 
 		partial void OnLoadedPartial()
 		{
-			this.EditingChanged += OnEditingChanged;
-			this.EditingDidEnd += OnEditingChanged;
+			SubscribeEditingEvents();
 		}
 
 		partial void OnUnloadedPartial()
 		{
-			this.EditingChanged -= OnEditingChanged;
-			this.EditingDidEnd -= OnEditingChanged;
+			UnsubscribeEditingEvents();
 		}
 
 		//Forces the secure UITextField to maintain its current value upon regaining focus
 		public override bool BecomeFirstResponder()
 		{
 			var result = base.BecomeFirstResponder();
 
-			if (SecureTextEntry)
+			if (SecureTextEntry && !string.IsNullOrEmpty(Text))
 			{
+				UnsubscribeEditingEvents();
+
 				var text = Text;
-				Text = string.Empty;
+				UpdatePasswordText(string.Empty);
 				InsertText(text);
+				UpdatePasswordText(text);
+
+				SubscribeEditingEvents();
 			}
 
 			return result;
+
+			void UpdatePasswordText(string text)
+			{
+				if (TextBox is PasswordBox passwordBox)
+				{
+					passwordBox.Password = text;
+				}
+			}
 		}
 
 		public override CGSize SizeThatFits(CGSize size)
@@ -261,5 +272,17 @@ public void Select(int start, int length)
 				}
 			}
 		}
+
+		private void SubscribeEditingEvents()
+		{
+			EditingChanged += OnEditingChanged;
+			EditingDidEnd += OnEditingChanged;
+		}
+
+		private void UnsubscribeEditingEvents()
+		{
+			EditingChanged -= OnEditingChanged;
+			EditingDidEnd -= OnEditingChanged;
+		}
 	}
 }