[iOS] Fix Picker CharacterSpacing lost after item selection when Title is set

[SyedAbdulAzeemSF4852]

Note

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It would be very helpful if you could test the resulting artifacts from this PR and let us know in a comment if this change resolves your issue. Thank you!

Issue Details

• When a Picker has both a Title and a non-zero CharacterSpacing, the character spacing is silently lost as soon as the user selects an item from the picker, or when SelectedIndex is changed programmatically. The spacing is visible before selection (applied to the placeholder/title text), but after any item is selected, the selected item renders without spacing.

Root Cause

• Regression: Introduced by PR [iOS] Fixed picker title's color #20205
• PR [iOS] Fixed picker title's color #20205 changed iOS Picker to apply CharacterSpacing via AttributedPlaceholder so the Title text respects kern. When the user selects an item, the code assigns a plain string to platformPicker.Text. iOS internally creates a zero-kern AttributedText from that plain string and simultaneously hides AttributedPlaceholder, since iOS never shows a placeholder when the text field has a value. This means the kern that was applied to the placeholder is gone, and no kern is applied to the selected item text — resulting in CharacterSpacing being silently lost after selection.

Description of Change

• After platformPicker.Text is set to the selected item's string, UpdateCharacterSpacing is now explicitly called to re-apply kern to AttributedText. This is done in two places: in UpdatePickerFromPickerSource (the Done-button code path in PickerHandler.iOS.cs) and in UpdatePicker (the programmatic SelectedIndex change path in PickerExtensions.cs), ensuring CharacterSpacing survives item selection regardless of how the selection is triggered.

Issues Fixed

Fixes #34971

Validated the behaviour in the following platforms

• Windows
• Android
• iOS
• Mac

Output

Before	After
Before.mov	After.mov

[github-actions]

🚀 Dogfood this PR with:

⚠️ WARNING: Do not do this without first carefully reviewing the code of this PR to satisfy yourself it is safe.

curl -fsSL https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.sh | bash -s -- 34974

Or

• Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 34974"

[Copilot]

Pull request overview

Fixes an iOS/MacCatalyst regression where Picker.CharacterSpacing is lost after an item is selected when Title is set, by re-applying kerning after the native text is assigned.

Changes:

• Re-apply CharacterSpacing after platformPicker.Text is set during selection updates (both programmatic and “Done” selection paths).
• Add an iOS device test to validate CharacterSpacing is preserved across SelectedIndex updates.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/Core/tests/DeviceTests/Handlers/Picker/PickerHandlerTests.iOS.cs	Adds a device test asserting character spacing is preserved when SelectedIndex changes programmatically.
src/Core/src/Platform/iOS/PickerExtensions.cs	Ensures UpdatePicker always re-applies character spacing after setting Text.
src/Core/src/Handlers/Picker/PickerHandler.iOS.cs	Re-applies character spacing after assigning Text in the “Done button” selection flow.

[kubaflo]

Could you please try the ai's suggestions?

[MauiBot]

Expert Review — 1 findings

See inline comments for details.

[MauiBot]

🤖 Automated review — alternative fix proposed

The expert-reviewer evaluation compared the PR fix against #1 automatically generated candidates and selected try-fix-1 as the strongest fix.

Why: try-fix-1 passed all 4 regression tests empirically using a SetTextWithCharacterSpacing helper that atomically constructs NSAttributedString with KerningAdjustment instead of the PR's fragile read-modify-write pattern. It also covers the OnEditing handler gap the PR missed and avoids the MacCatalyst test crash entirely.

Please consider applying the candidate diff below (or use it as guidance). Once you push an update, this workflow will re-trigger and re-evaluate.

Candidate diff (`try-fix-1`)

diff --git a/src/Core/src/Handlers/Picker/PickerHandler.iOS.cs b/src/Core/src/Handlers/Picker/PickerHandler.iOS.cs
index a54299d290..11fe557578 100644
--- a/src/Core/src/Handlers/Picker/PickerHandler.iOS.cs
+++ b/src/Core/src/Handlers/Picker/PickerHandler.iOS.cs
@@ -255,7 +255,7 @@ namespace Microsoft.Maui.Handlers
 			if (VirtualView == null || PlatformView == null || pickerSource == null)
 				return;
 
-			PlatformView.Text = VirtualView.GetItem(pickerSource.SelectedIndex);
+			PlatformView.SetTextWithCharacterSpacing(VirtualView.GetItem(pickerSource.SelectedIndex), VirtualView.CharacterSpacing);
 			VirtualView.SelectedIndex = pickerSource.SelectedIndex;
 		}
 
@@ -423,7 +423,7 @@ namespace Microsoft.Maui.Handlers
 				// Reset the TextField's Text so it appears as if typing with a keyboard does not work.
 				var selectedIndex = virtualView.SelectedIndex;
 
-				platformView.Text = virtualView.GetItem(selectedIndex);
+				platformView.SetTextWithCharacterSpacing(virtualView.GetItem(selectedIndex), virtualView.CharacterSpacing);
 
 				// Also clears the undo stack (undo/redo possible on iPads)
 				platformView.UndoManager?.RemoveAllActions();
diff --git a/src/Core/src/Platform/iOS/PickerExtensions.cs b/src/Core/src/Platform/iOS/PickerExtensions.cs
index c2de04d1fd..13e429ae28 100644
--- a/src/Core/src/Platform/iOS/PickerExtensions.cs
+++ b/src/Core/src/Platform/iOS/PickerExtensions.cs
@@ -1,6 +1,7 @@
 #nullable enable
 using System;
 using Foundation;
+using UIKit;
 
 namespace Microsoft.Maui.Platform
 {
@@ -36,18 +37,45 @@ namespace Microsoft.Maui.Platform
 			platformPicker.UpdateAttributedPlaceholder(new NSAttributedString(picker.Title ?? string.Empty, null, picker?.TitleColor?.ToPlatform()));
 		}
 
+		/// <summary>
+		/// Sets text on a picker using AttributedText with kern to avoid iOS clearing
+		/// character spacing when plain Text is assigned.
+		/// </summary>
+		/// <remarks>
+		/// Unlike UpdateCharacterSpacing (which reads back AttributedText and adds kern),
+		/// this creates a fresh NSAttributedString to work around an iOS issue where
+		/// reading AttributedText immediately after setting Text doesn't reliably
+		/// preserve kern in all handler lifecycle contexts.
+		/// </remarks>
+		internal static void SetTextWithCharacterSpacing(this MauiPicker platformPicker, string text, double characterSpacing)
+		{
+			if (characterSpacing == 0)
+			{
+				platformPicker.Text = text;
+				return;
+			}
+
+			var attributes = new UIKit.UIStringAttributes
+			{
+				KerningAdjustment = (float)characterSpacing
+			};
+			platformPicker.AttributedText = new NSAttributedString(text ?? string.Empty, attributes);
+		}
+
 		internal static void UpdatePicker(this MauiPicker platformPicker, IPicker picker, int? newSelectedIndex = null)
 		{
 			var selectedIndex = newSelectedIndex ?? picker.SelectedIndex;
 
 			if (selectedIndex != -1)
 			{
-				platformPicker.Text = picker.GetItem(selectedIndex);
+				platformPicker.SetTextWithCharacterSpacing(picker.GetItem(selectedIndex), picker.CharacterSpacing);
 			}
 			else
 			{
 				platformPicker.Text = null;
 				platformPicker.UpdatePickerTitle(picker);
+				// Applies character spacing to the placeholder when no item is selected
+				platformPicker.UpdateCharacterSpacing(picker);
 			}
 
 			var pickerView = platformPicker.UIPickerView;

Resetting for re-review