[iOS 26] Fix NavigationPage.TitleView not resizing on rotation

[Copilot]

Note

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Description of Change

On iOS 26+ and MacCatalyst 26+, NavigationPage.TitleView fails to resize when device orientation changes. The view retains its initial width instead of expanding/contracting to fill the navigation bar.

Root cause: iOS 26 changed autoresizing behavior. While UIViewAutoresizing.FlexibleWidth handles width adjustments, the frame must be explicitly updated during trait collection changes to use the full navigation bar width.

Fix:

• Override TraitCollectionDidChange in NavigationRenderer.PageContainer to detect orientation changes (size class transitions)
• Explicitly update TitleView frame to match navigation bar dimensions on iOS 26+/MacCatalyst 26+
• Only applies to iOS 26+ where the regression exists

Code change:

public override void TraitCollectionDidChange(UITraitCollection previousTraitCollection)
{
    base.TraitCollectionDidChange(previousTraitCollection);
    
    if (previousTraitCollection?.VerticalSizeClass != TraitCollection.VerticalSizeClass ||
        previousTraitCollection?.HorizontalSizeClass != TraitCollection.HorizontalSizeClass)
    {
        if (OperatingSystem.IsIOSVersionAtLeast(26) || OperatingSystem.IsMacCatalystVersionAtLeast(26))
        {
            UpdateTitleViewFrameForOrientation();
        }
    }
}

Issues Fixed

Fixes dotnet#32722

Original prompt

please review dotnet#32815

Custom agent used: pr-reviewer
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[kubaflo]

@copilot I've tested and it passes my manual testing

[kubaflo]

@copilot Can you create the review file?

[Copilot]

@copilot Can you create the review file?

Code review completed. Found 3 items for consideration:

1. NavigationRenderer.cs (line 1613-1616): Comment formatting - missing period after "FlexibleWidth"
2. Issue32722.cs (lines 28, 46): Using Thread.Sleep in tests can be brittle. Consider async/await with Task.Delay or waiting for specific UI states

Overall, the fix is well-targeted and addresses the iOS 26+ regression appropriately by:

• ✅ Only applying the fix to iOS/MacCatalyst 26+
• ✅ Detecting orientation changes via trait collection
• ✅ Explicitly updating TitleView frame to match navigation bar
• ✅ Including comprehensive UI test coverage