iOS Touch Event Bug Reproduction (MAUI 10.0.60)

This repository reproduces a severe regression bug introduced in .NET MAUI 10.0.60 where touch events on elements inside a ContentView or LayoutView permanently stop working on iOS if the wrapper's opacity is animated and its parent's IsEnabled property is toggled, provided the wrapper does not have an explicit background color.

Bug Overview

When navigating or loading states, developers often toggle a layout's visibility, disable it (IsEnabled = false), and fade views out to transparent (Opacity = 0.0).

In .NET MAUI 10.0.60, if IsEnabled on a parent layout is toggled while a ContentView or LayoutView with no explicit background color is faded out, MAUI sets the native iOS view's background to null.

Once the sequence completes and the view is faded back in, the iOS UIView representing the ContentView remains completely transparent to touches (it fails hit testing). Touch event handlers on children (like SKCanvasView) are no longer triggered because their parent swallows or ignores the hit tests, breaking all user interaction with the control.

This bug does not occur in .NET MAUI 10.0.50.

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The Missing Link: Why raw SKCanvasView works, but ContentView fails

If you call FadeToAsync(0.0) directly on a raw SKCanvasView that is placed directly in the layout, the touch events will work correctly in 10.0.60.

This is because the MAUI 10.0.60 bug introduced in PR #31340 has a very specific type check:

// src/Core/src/Platform/iOS/ViewExtensions.cs
if (paint.IsNullOrEmpty())
{
    if (platformView is LayoutView or ContentView) // <--- CRITICAL CONDITION
        platformView.BackgroundColor = null;
    else
        return;
}

SKCanvasView translates natively to a UIView, which is neither a LayoutView nor a ContentView in MAUI's native hierarchy. Therefore, it bypasses the buggy assignment.

To trigger the bug, the view being faded must be a ContentView or LayoutView (e.g. a custom control inheriting from ContentView that wraps the SKCanvasView).

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Steps to Reproduce

1. Run this application on an iOS Simulator or Device.
2. Tap the "Trigger Fade Sequence" button.
3. Wait for the sequence to complete.
4. Tap the red rectangle (the SKCanvasView wrapped in a ContentView).
5. Observe the result:
   • Under .NET MAUI 10.0.50 (or if the bug is fixed), the label updates to "Touch detected!".
   • Under .NET MAUI 10.0.60, nothing happens. The touch event handler never fires because the ContentView wrapper's native background is null.

---

Proposed Fix

To fix this bug in .NET MAUI, the framework should avoid assigning null to the background color when a background paint is empty. Instead, it should assign UIColor.Clear which keeps it visually transparent while ensuring hit tests and touch events continue to function correctly.

Framework Diff:

diff --git a/src/Core/src/Platform/iOS/ViewExtensions.cs b/src/Core/src/Platform/iOS/ViewExtensions.cs
index a5b1c2b..d3fe90a 100644
--- a/src/Core/src/Platform/iOS/ViewExtensions.cs
+++ b/src/Core/src/Platform/iOS/ViewExtensions.cs
@@ -84,7 +84,7 @@ namespace Microsoft.Maui.Platform
  			if (paint.IsNullOrEmpty())
  			{
  				if (platformView is LayoutView or ContentView)
-					platformView.BackgroundColor = null;
+					platformView.BackgroundColor = UIColor.Clear;
  				else
  					return;
  			}