[iOS] Fix Switch ThumbColor reset on iOS 26+ theme changes. by Shalini-Ashokan · Pull Request #33953 · dotnet/maui

Shalini-Ashokan · 2026-02-09T10:00:36Z

Note

Are you waiting for the changes in this PR to be merged?
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

On iOS/MacCatalyst 26+, when the app theme changes (light ↔ dark), the Switch's ThumbColor resets to white instead of keeping the custom color.

Root Cause

On iOS/MacCatalyst 26+, UIKit resets the UISwitch's ThumbTintColor to its default value during theme transitions.

Description of Change

Register for trait collection changes to detect theme switches, then re-apply the custom ThumbColor after UIKit completes its styling.

Validated the behavior in the following platforms

Android
Windows
iOS
Mac

Issues Fixed

Fixes #33783
Fixes #33767

Output ScreenShot

Before	After
33783-BeforeFix.mov	33783-AfterFix.mov

sheiksyedm · 2026-02-10T06:50:08Z

/azp run maui-pr-uitests

azure-pipelines · 2026-02-10T06:50:19Z

Azure Pipelines successfully started running 1 pipeline(s).

sheiksyedm · 2026-02-18T11:55:34Z

/rebase

github-actions · 2026-02-27T08:09:43Z

🚀 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 -- 33953

Or

Run remotely in PowerShell:

iex "& { $(irm https://raw.githubusercontent.com/dotnet/maui/main/eng/scripts/get-maui-pr.ps1) } 33953"

Copilot

Pull request overview

Fixes an iOS/MacCatalyst 26+ behavior where UISwitch.ThumbTintColor gets reset during theme (light/dark) changes by re-applying the custom thumb color after trait changes and adding a UI test scenario.

Changes:

Register for UITraitUserInterfaceStyle changes on iOS/MacCatalyst 26+ and re-apply ThumbColor.
Add a delayed re-apply path for thumb color to allow UIKit styling to finish.
Add a new issue page + UI test coverage for the theme-change scenario.

Reviewed changes

Copilot reviewed 3 out of 13 changed files in this pull request and generated 4 comments.

File	Description
src/Core/src/Handlers/Switch/SwitchHandler.iOS.cs	Re-applies thumb color on trait (theme) changes for iOS/MacCatalyst 26+.
src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33783.cs	Adds screenshot-based UI tests for switching themes.
src/Controls/tests/TestCases.HostApp/Issues/Issue33783.cs	Adds a host app repro page with theme toggle buttons and a custom-colored switch.

kubaflo

Looks like the test succeeds without a fix

sheiksyedm · 2026-03-31T13:15:45Z

/azp run maui-pr-uitests

azure-pipelines · 2026-03-31T13:15:58Z

Azure Pipelines successfully started running 1 pipeline(s).

jfversluis · 2026-04-01T11:36:23Z

/rebase

azure-pipelines · 2026-04-01T11:39:58Z

Azure Pipelines successfully started running 1 pipeline(s).

MauiBot · 2026-04-01T14:19:39Z

🚦 Gate - Test Before and After Fix

📊 Expand Full Gate — 39a41f2 · Resolved the gate failures

Gate Result: ❌ FAILED

Platform: IOS · Base: main · Merge base: b43bdad1

Test	Without Fix (expect FAIL)	With Fix (expect PASS)
🖥️ Issue33783 `Issue33783`	❌ PASS — 227s	✅ PASS — 93s

🔴 Without fix — 🖥️ Issue33783: PASS ❌ · 227s

  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 644 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 968 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 11.37 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/Foldable/src/Controls.Foldable.csproj (in 13.59 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Xaml/Controls.Xaml.csproj (in 13.61 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/Maps/src/Controls.Maps.csproj (in 13.62 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 13.62 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/maps/src/Maps.csproj (in 13.62 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 13.62 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/BlazorWebView/src/Maui/Microsoft.AspNetCore.Components.WebView.Maui.csproj (in 13.62 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj (in 13.63 sec).
/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0-ios26.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0-ios26.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0-ios26.0/Microsoft.Maui.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Maps.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Microsoft.AspNetCore.Components.WebView.Maui -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Microsoft.AspNetCore.Components.WebView.Maui/Debug/net10.0-ios26.0/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Controls.Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Maps.dll
  Controls.Foldable -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Foldable/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Foldable.dll
  Controls.Xaml -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Xaml.dll
  Detected signing identity:
    Code Signing Key: "" (-)
    Provisioning Profile: "" () - no entitlements
    Bundle Id: com.microsoft.maui.uitests
    App Id: com.microsoft.maui.uitests
  Controls.TestCases.HostApp -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-ios/iossimulator-arm64/Controls.TestCases.HostApp.dll
  Optimizing assemblies for size may change the behavior of the app. Be sure to test after publishing. See: https://aka.ms/dotnet-illink
  Optimizing assemblies for size. This process might take a while.

Build succeeded.

/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
    1 Warning(s)
    0 Error(s)

Time Elapsed 00:01:42.65
  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.Core/UITest.Core.csproj (in 676 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/VisualTestUtils/VisualTestUtils.csproj (in 676 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/tests/CustomAttributes/Controls.CustomAttributes.csproj (in 676 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 693 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 677 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 675 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 1.03 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 530 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.NUnit/UITest.NUnit.csproj (in 1.54 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.Appium/UITest.Appium.csproj (in 2.12 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/UITest.Analyzers/UITest.Analyzers.csproj (in 3.78 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/TestUtils/src/VisualTestUtils.MagickNet/VisualTestUtils.MagickNet.csproj (in 11.83 sec).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.iOS.Tests/Controls.TestCases.iOS.Tests.csproj (in 12.57 sec).
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Controls.CustomAttributes -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.CustomAttributes/Debug/net10.0/Controls.CustomAttributes.dll
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  UITest.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Core/Debug/net10.0/UITest.Core.dll
  VisualTestUtils -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils/Debug/netstandard2.0/VisualTestUtils.dll
  UITest.NUnit -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.NUnit/Debug/net10.0/UITest.NUnit.dll
  UITest.Appium -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Appium/Debug/net10.0/UITest.Appium.dll
  VisualTestUtils.MagickNet -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils.MagickNet/Debug/netstandard2.0/VisualTestUtils.MagickNet.dll
  UITest.Analyzers -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Analyzers/Debug/netstandard2.0/UITest.Analyzers.dll
  Controls.TestCases.iOS.Tests -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
Test run for /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (arm64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
/Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.04]   Discovering: Controls.TestCases.iOS.Tests
[xUnit.net 00:00:00.14]   Discovered:  Controls.TestCases.iOS.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
   NUnit3TestExecutor discovered 2 of 2 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 4/9/2026 7:55:29 AM FixtureSetup for Issue33783(iOS)
>>>>> 4/9/2026 7:55:33 AM VerifySwitchThumbColorOnDarkThemeChange Start
>>>>> 4/9/2026 7:55:34 AM VerifySwitchThumbColorOnDarkThemeChange Stop
  Passed VerifySwitchThumbColorOnDarkThemeChange [1 s]
>>>>> 4/9/2026 7:55:34 AM VerifySwitchThumbColorOnLightThemeChange Start
>>>>> 4/9/2026 7:55:36 AM VerifySwitchThumbColorOnLightThemeChange Stop
  Passed VerifySwitchThumbColorOnLightThemeChange [1 s]
NUnit Adapter 4.5.0.0: Test execution complete

Test Run Successful.
Total tests: 2
     Passed: 2
 Total time: 1.0360 Minutes

🟢 With fix — 🖥️ Issue33783: PASS ✅ · 93s

  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 388 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 393 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 398 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 424 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 437 ms).
  6 of 11 projects are up-to-date for restore.
/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0-ios26.0/Microsoft.Maui.Graphics.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0-ios26.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0-ios26.0/Microsoft.Maui.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Maps.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Controls.Maps -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Maps/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Maps.dll
  Controls.Xaml -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Xaml/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Xaml.dll
  Controls.Foldable -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Foldable/Debug/net10.0-ios26.0/Microsoft.Maui.Controls.Foldable.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Microsoft.AspNetCore.Components.WebView.Maui -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Microsoft.AspNetCore.Components.WebView.Maui/Debug/net10.0-ios26.0/Microsoft.AspNetCore.Components.WebView.Maui.dll
  Detected signing identity:
    Code Signing Key: "" (-)
    Provisioning Profile: "" () - no entitlements
    Bundle Id: com.microsoft.maui.uitests
    App Id: com.microsoft.maui.uitests
  Controls.TestCases.HostApp -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.HostApp/Debug/net10.0-ios/iossimulator-arm64/Controls.TestCases.HostApp.dll
  Optimizing assemblies for size may change the behavior of the app. Be sure to test after publishing. See: https://aka.ms/dotnet-illink
  Optimizing assemblies for size. This process might take a while.

Build succeeded.

/Users/cloudtest/vss/_work/1/s/.dotnet/packs/Microsoft.iOS.Sdk.net10.0_26.0/26.0.11017/targets/Xamarin.Shared.Sdk.targets(309,3): warning : RuntimeIdentifier was set on the command line, and will override the value for RuntimeIdentifiers set in the project file. [/Users/cloudtest/vss/_work/1/s/src/Controls/tests/TestCases.HostApp/Controls.TestCases.HostApp.csproj::TargetFramework=net10.0-ios]
    1 Warning(s)
    0 Error(s)

Time Elapsed 00:00:44.64
  Determining projects to restore...
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/BindingSourceGen/Controls.BindingSourceGen.csproj (in 412 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Graphics/src/Graphics/Graphics.csproj (in 369 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Essentials/src/Essentials.csproj (in 422 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Core/src/Core.csproj (in 453 ms).
  Restored /Users/cloudtest/vss/_work/1/s/src/Controls/src/Core/Controls.Core.csproj (in 467 ms).
  8 of 13 projects are up-to-date for restore.
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Graphics -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Graphics/Debug/net10.0/Microsoft.Maui.Graphics.dll
  Controls.CustomAttributes -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.CustomAttributes/Debug/net10.0/Controls.CustomAttributes.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Essentials -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Essentials/Debug/net10.0/Microsoft.Maui.Essentials.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Core/Debug/net10.0/Microsoft.Maui.dll
  Controls.BindingSourceGen -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.BindingSourceGen/Debug/netstandard2.0/Microsoft.Maui.Controls.BindingSourceGen.dll
  ##vso[build.updatebuildnumber]10.0.60-ci+azdo.13788332
  Controls.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.Core/Debug/net10.0/Microsoft.Maui.Controls.dll
  UITest.Core -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Core/Debug/net10.0/UITest.Core.dll
  VisualTestUtils -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils/Debug/netstandard2.0/VisualTestUtils.dll
  UITest.Appium -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Appium/Debug/net10.0/UITest.Appium.dll
  UITest.NUnit -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.NUnit/Debug/net10.0/UITest.NUnit.dll
  VisualTestUtils.MagickNet -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/VisualTestUtils.MagickNet/Debug/netstandard2.0/VisualTestUtils.MagickNet.dll
  UITest.Analyzers -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/UITest.Analyzers/Debug/netstandard2.0/UITest.Analyzers.dll
  Controls.TestCases.iOS.Tests -> /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
Test run for /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll (.NETCoreApp,Version=v10.0)
VSTest version 18.0.1 (arm64)

Starting test execution, please wait...
A total of 1 test files matched the specified pattern.
/Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
[xUnit.net 00:00:00.00] xUnit.net VSTest Adapter v2.8.2+699d445a1a (64-bit .NET 10.0.0)
[xUnit.net 00:00:00.05]   Discovering: Controls.TestCases.iOS.Tests
[xUnit.net 00:00:00.16]   Discovered:  Controls.TestCases.iOS.Tests
NUnit Adapter 4.5.0.0: Test execution started
Running selected tests in /Users/cloudtest/vss/_work/1/s/artifacts/bin/Controls.TestCases.iOS.Tests/Debug/net10.0/Controls.TestCases.iOS.Tests.dll
   NUnit3TestExecutor discovered 2 of 2 NUnit test cases using Current Discovery mode, Non-Explicit run
>>>>> 4/9/2026 7:57:01 AM FixtureSetup for Issue33783(iOS)
>>>>> 4/9/2026 7:57:05 AM VerifySwitchThumbColorOnDarkThemeChange Start
>>>>> 4/9/2026 7:57:07 AM VerifySwitchThumbColorOnDarkThemeChange Stop
  Passed VerifySwitchThumbColorOnDarkThemeChange [1 s]
>>>>> 4/9/2026 7:57:07 AM VerifySwitchThumbColorOnLightThemeChange Start
>>>>> 4/9/2026 7:57:08 AM VerifySwitchThumbColorOnLightThemeChange Stop
  Passed VerifySwitchThumbColorOnLightThemeChange [1 s]
NUnit Adapter 4.5.0.0: Test execution complete

Test Run Successful.
Total tests: 2
     Passed: 2
 Total time: 20.9962 Seconds

⚠️ Issues found

❌ Issue33783 PASSED without fix (should fail) — tests don't catch the bug

📁 Fix files reverted (2 files)

eng/pipelines/ci-copilot.yml
src/Core/src/Handlers/Switch/SwitchHandler.iOS.cs

MauiBot · 2026-04-01T16:45:16Z

🤖 AI Summary

📊 Expand Full Review — 39a41f2 · Resolved the gate failures

🔍 Pre-Flight — Context & Validation

Issue: #33783 - Switch ThumbColor not Initialized Using VisualStateManager on iOS Device (iOS 26+)
Issue: #33767 - On macOS 26.2, the "Animate scroll" button is white by default on iOS and MacCatalyst platforms (tangentially related — also a color reset issue on iOS/macCatalyst 26+)
PR: #33953 - [iOS] Fix Switch ThumbColor reset on iOS 26+ theme changes.
Platforms Affected: iOS 26+, MacCatalyst 26+
Files Changed: 1 implementation, 12 test/snapshot files

Key Findings

Root cause: On iOS/MacCatalyst 26+, UIKit resets UISwitch.ThumbTintColor to its default during theme transitions (light ↔ dark) and possibly during initial layout.
Fix approach: Register for UITraitUserInterfaceStyle trait changes on iOS/macCatalyst 26+, re-apply ThumbColor asynchronously (with 10ms delay) after trait change fires.
Gate ❌ FAILED: Tests PASSED even WITHOUT the fix (227s), meaning the screenshot tests do not detect the ThumbColor reset bug. The tests are using pre-captured baselines that may have been captured WITH the bug present or on a platform where it doesn't manifest (simulator vs device).
Code quality concern: UpdateThumbColor uses DispatchAsync(async () => ...) creating an async void — unobserved exceptions possible. The Task.Delay(10) inside creates a race: delayed continuation runs after Disconnect, applying stale state to an already-disconnected platform view.
The UpdateThumbColor method takes platformView as a parameter but checks PlatformView (weak ref) after the delay — correct behavior, but the final call uses the captured platformView parameter (may be stale after disconnect).
Tests use await Task.Delay(500) before VerifyScreenshot — anti-pattern per test guidelines; should use VerifyScreenshot(retryTimeout: ...).
Issue I9-On macOS 26.2, the "Animate scroll" button is white by default on iOS and Maccatalyst platforms. #33767 is about a CollectionView "Animate scroll" button being white — the PR claims to fix it but test cases only cover the Switch scenario from Switch ThumbColor not Initialized Using VisualStateManager on iOS Device #33783.
The _traitChangeRegistration guard in Connect (checking if not null before unregistering) is cited by the PR author as "never executes in practice" since Disconnect always precedes Connect. This assertion appears valid given MAUI's handler lifecycle.
Snapshot files added for: android, mac, windows, ios, ios-26 variants.

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
PR	PR #33953	Register `UITraitUserInterfaceStyle` change on iOS/macCatalyst 26+; re-apply ThumbColor async (10ms delay)	⏳ PENDING (Gate ❌ FAILED)	`SwitchHandler.iOS.cs`	async void race concern; test flakiness concern

🔧 Fix — Analysis & Comparison

Fix Candidates

#	Source	Approach	Test Result	Files Changed	Notes
1	try-fix	MauiSwitch override re-applies stored ThumbColor synchronously	subclass PASS	3 files (new MauiSwitch.cs, SwitchHandler.iOS.cs, SwitchExtensions.cs)	Synchronous, no async delay
2	try-fix	KVO on PASS	SwitchHandler.iOS.cs + ios-26 snapshots	Also identified gate failure root cause
3	try-fix	override in synchronous re-apply, no registration object	SwitchProxy PASS	SwitchHandler.iOS.cs	Clean override, no external registration
4	try-fix	wraps UIKit preserves adaptive color through trait changes	ThumbColor PASS	SwitchExtensions.cs only	Most idiomatic iOS 17+ approach. Single-file, minimal change
5	try-fix	Preventive property override in blocks UIKits nil writes	subclass PASS	3 files (new MauiSwitch.cs, SwitchHandler.iOS.cs, SwitchExtensions.cs)	Most robust prevention, zero timing window
PR	PR #33953	Register `UITraitUserInterfaceStyle` changes + `DispatchAsync(async () => { Task.Delay( FAILED	SwitchHandler.iOS.cs	async void race; wrong iOS version in CI	Gate 10); })`

Cross-Pollination

Model	Round	New Ideas?	Details
became Attempt #5 (PASS)
gpt-5.3-codex	2	YES	Custom thumb UIImage instead of overly invasive, not pursued
gpt-5.4	2	YES	TintColorDidChange variant of Attempt #3, not pursued

Exhausted: further ideas are variants of existing passing approaches or increasingly invasiveYes
Selected Fix: Candidate #4 (Dynamic UIColor via UIColor. single file change in SwitchExtensions.cs, most idiomatic iOS 17+ approach, works with UIKit's color system rather than fighting itFromDynamicProvider)

📋 Report — Final Recommendation

⚠️ Final Recommendation: REQUEST CHANGES

Phase Status

Phase	Status	Notes
Pre-Flight	✅ COMPLETE	Issues #33783, #33767 — Switch ThumbColor reset on iOS/macCatalyst 26+
Gate	❌ FAILED	iOS — tests PASS without fix (iOS 18 simulator used; bug only manifests on iOS 26)
Try-Fix	✅ COMPLETE	5 attempts, all 5 PASSING; better alternatives found
Report	✅ COMPLETE

Summary

PR #33953 addresses a real bug on iOS/macCatalyst 26+ where UIKit resets UISwitch.ThumbTintColor during theme transitions. The fix is functionally correct but has several issues that warrant changes before merging:

Gate failed — The tests pass even without the fix because the CI environment uses iOS 18, where the bug does not manifest. The snapshots must target an iOS 26 simulator to be meaningful.
Code quality concerns — The UpdateThumbColor helper uses DispatchAsync(async () => { await Task.Delay(10); ... }), creating an async void with an unobserved-exception risk, plus a timing race: the 10ms delayed continuation can fire after Disconnect and apply stale state.
Better alternative found — Try-Fix Candidate Aloha System.Maui! #4 achieves the same result more idiomatically with a single-file change.

Root Cause

On iOS/macCatalyst 26+, UIKit introduced a new theming pass during UITraitUserInterfaceStyle transitions that resets UISwitch.ThumbTintColor to nil. This resets any explicitly set custom thumb color. The same reset can also occur during initial layout on iOS 26+.

Fix Quality

PR's approach (trait registration + async delay):

✅ Correct conceptual approach — listening for the UIKit reset event
✅ Properly cleans up _traitChangeRegistration in Disconnect
❌ DispatchAsync(async () => { await Task.Delay(10); ... }) is effectively async void — unobserved exceptions from Task.Delay or subsequent code
❌ Race condition: the platformView parameter captured in the lambda can be stale if Disconnect fires before the 10ms delay completes; while the PlatformView weak-ref null check partially guards this, the check and platformView.UpdateThumbColor(view) call use different references
❌ Tests use await Task.Delay(500) before VerifyScreenshot — should use VerifyScreenshot(retryTimeout: TimeSpan.FromSeconds(2)) per test guidelines
❌ Gate fails because tests pass without fix (iOS 18 CI, wrong platform for this bug)

Recommended alternative — Candidate #4 (Dynamic UIColor):

// In SwitchExtensions.UpdateThumbColor, on iOS/MacCatalyst 17+:
// Wrap the custom color in UIColor.Create(light:dark:) so UIKit treats it
// as a dynamic color and never discards it during trait/theme transitions.
public static void UpdateThumbColor(this UISwitch uiSwitch, ISwitch view)
{
    if (view == null) return;
    var thumbColor = view.ThumbColor;
    if (thumbColor != null)
    {
        var platform = thumbColor.ToPlatform();
        if (OperatingSystem.IsIOSVersionAtLeast(17) || OperatingSystem.IsMacCatalystVersionAtLeast(17))
            uiSwitch.ThumbTintColor = UIColor.Create(traitCollection => platform);
        else
            uiSwitch.ThumbTintColor = platform;
    }
}

✅ Single file change (SwitchExtensions.cs)
✅ No callbacks, no subclass, no async dispatch, no timing windows
✅ Works with UIKit's color system — UIKit resolves and re-resolves dynamic colors; never resets them to nil
✅ Passed tests on iOS 26 simulator

Required Changes

Fix the gate test environment — Ensure the snapshot baselines and test run target iOS 26 where the bug manifests; add ios-26 snapshot variants with correct (red) thumb color
Fix UpdateThumbColor async void — Either apply Candidate Aloha System.Maui! #4's dynamic-UIColor approach (no callbacks needed), or at minimum replace DispatchAsync(async () => ...) with a DispatchAfter call (no async/await) and add a check that PlatformView == platformView before applying
Fix test delay pattern — Replace await Task.Delay(500) with VerifyScreenshot(retryTimeout: TimeSpan.FromSeconds(2)) per test guidelines
Verify issue I9-On macOS 26.2, the "Animate scroll" button is white by default on iOS and Maccatalyst platforms. #33767 — That issue is about a CollectionView "Animate scroll" button being white, but the PR only adds tests for Switch ThumbColor. Confirm whether the Switch fix also resolves I9-On macOS 26.2, the "Animate scroll" button is white by default on iOS and Maccatalyst platforms. #33767 or whether it is a separate issue

Shalini-Ashokan · 2026-04-02T10:25:37Z

🤖 AI Summary

📊 Expand Full Review — 0807361 · committed the windows snapshot

Replace async void with DispatchAfter — Not needed. This follows the same DispatchAsync(async () => ...) pattern already used by UpdateTrackOffColor in the same file. Changing only the new code creates inconsistency.
Add _disconnected guard flag — Not needed. VirtualView and PlatformView are WeakReference-backed properties that already return null after disconnect. The null checks on lines 151-152 handle this.
Add retryTimeout to VerifyScreenshot — Addressed with Task.Delay(500) instead, to let UIKit complete its theme transition and ThumbTintColor reset before capturing. This explicit delay better matches the specific timing needed for this bug's reproduction.
Remove I9-On macOS 26.2, the "Animate scroll" button is white by default on iOS and Maccatalyst platforms. #33767 from "Fixes" — Not applicable. Issue I9-On macOS 26.2, the "Animate scroll" button is white by default on iOS and Maccatalyst platforms. #33767 is also caused by the same iOS 26+ ThumbTintColor reset behavior, and this PR's changes resolve it. Keeping it as a linked fix is correct.
Add initial state screenshot test — Not required. The test already verifies correct ThumbColor after each theme change, and the initial state is implicitly confirmed when those screenshots match the expected red thumb.

azure-pipelines · 2026-04-09T12:32:27Z

Azure Pipelines successfully started running 1 pipeline(s).

> [!NOTE] > Are you waiting for the changes in this PR to be merged? > It would be very helpful if you could [test the resulting artifacts](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from this PR and let us know in a comment if this change resolves your issue. Thank you!  ### Issue Details On iOS/MacCatalyst 26+, when the app theme changes (light ↔ dark), the Switch's ThumbColor resets to white instead of keeping the custom color. ### Root Cause On iOS/MacCatalyst 26+, UIKit resets the UISwitch's ThumbTintColor to its default value during theme transitions. ### Description of Change Register for trait collection changes to detect theme switches, then re-apply the custom ThumbColor after UIKit completes its styling. Validated the behavior in the following platforms - [x] Android - [x] Windows - [x] iOS - [x] Mac ### Issues Fixed Fixes #33783 Fixes #33767 ### Output ScreenShot |Before|After| |--|--| | <video src="https://github.com/user-attachments/assets/aa595096-4f75-4d7e-b31e-f1f0acc24208" >| <video src="https://github.com/user-attachments/assets/386f9e6e-6df7-40c5-a3e7-59a0bde31df6">|

…3953)  > [!NOTE] > Are you waiting for the changes in this PR to be merged? > It would be very helpful if you could [test the resulting artifacts](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from this PR and let us know in a comment if this change resolves your issue. Thank you!  ### Issue Details On iOS/MacCatalyst 26+, when the app theme changes (light ↔ dark), the Switch's ThumbColor resets to white instead of keeping the custom color. ### Root Cause On iOS/MacCatalyst 26+, UIKit resets the UISwitch's ThumbTintColor to its default value during theme transitions. ### Description of Change Register for trait collection changes to detect theme switches, then re-apply the custom ThumbColor after UIKit completes its styling. Validated the behavior in the following platforms - [x] Android - [x] Windows - [x] iOS - [x] Mac ### Issues Fixed Fixes dotnet#33783 Fixes dotnet#33767 ### Output ScreenShot |Before|After| |--|--| | <video src="https://github.com/user-attachments/assets/aa595096-4f75-4d7e-b31e-f1f0acc24208" >| <video src="https://github.com/user-attachments/assets/386f9e6e-6df7-40c5-a3e7-59a0bde31df6">|

> [!NOTE] > Are you waiting for the changes in this PR to be merged? > It would be very helpful if you could [test the resulting artifacts](https://github.com/dotnet/maui/wiki/Testing-PR-Builds) from this PR and let us know in a comment if this change resolves your issue. Thank you!  ### Issue Details On iOS/MacCatalyst 26+, when the app theme changes (light ↔ dark), the Switch's ThumbColor resets to white instead of keeping the custom color. ### Root Cause On iOS/MacCatalyst 26+, UIKit resets the UISwitch's ThumbTintColor to its default value during theme transitions. ### Description of Change Register for trait collection changes to detect theme switches, then re-apply the custom ThumbColor after UIKit completes its styling. Validated the behavior in the following platforms - [x] Android - [x] Windows - [x] iOS - [x] Mac ### Issues Fixed Fixes #33783 Fixes #33767 ### Output ScreenShot |Before|After| |--|--| | <video src="https://github.com/user-attachments/assets/aa595096-4f75-4d7e-b31e-f1f0acc24208" >| <video src="https://github.com/user-attachments/assets/386f9e6e-6df7-40c5-a3e7-59a0bde31df6">|

dotnet-policy-service Bot added community ✨ Community Contribution partner/syncfusion Issues / PR's with Syncfusion collaboration labels Feb 9, 2026

karthikraja-arumugam added platform/ios area-controls-switch Switch labels Feb 9, 2026

build-analysis Bot mentioned this pull request Feb 9, 2026

System.Exception : Failed to launch Test AVD. #33862

Open

github-actions Bot force-pushed the fix-33783 branch from efb01ce to 5fef81c Compare February 18, 2026 11:56

Shalini-Ashokan force-pushed the fix-33783 branch from f5b70f6 to 6a2e393 Compare February 27, 2026 08:18

build-analysis Bot mentioned this pull request Feb 27, 2026

NuGet failing with Response status code does not indicate success: 503 (Service Unavailable) dotnet/arcade#11723

Open

5 tasks

sheiksyedm marked this pull request as ready for review March 24, 2026 07:21

Copilot AI review requested due to automatic review settings March 24, 2026 07:21

Copilot started reviewing on behalf of sheiksyedm March 24, 2026 07:22 View session

Copilot AI reviewed Mar 24, 2026

View reviewed changes

Comment thread src/Core/src/Handlers/Switch/SwitchHandler.iOS.cs

Comment thread src/Core/src/Handlers/Switch/SwitchHandler.iOS.cs

Comment thread src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33783.cs

Comment thread src/Controls/tests/TestCases.Shared.Tests/Tests/Issues/Issue33783.cs

MauiBot added s/agent-changes-requested AI agent recommends changes - found a better alternative or issues s/agent-reviewed PR was reviewed by AI agent workflow (full 4-phase review) labels Mar 28, 2026

kubaflo requested changes Mar 28, 2026

View reviewed changes

Shalini-Ashokan added 3 commits April 1, 2026 11:37

Fixed the switch thumb color is wrong when theme changes

3d5bef2

Simplified the fix

29063bd

modified the fix

a66b6b0

Shalini-Ashokan added 5 commits April 1, 2026 11:37

Added test cases

f4e8c56

Added snapshots

bb6b7e9

Fixed the switch thumb color is wrong when theme changes

af5a556

Simplified the fix

877a3e2

Resolved the compilation issue

7750db7

github-actions Bot force-pushed the fix-33783 branch from f60367d to 7750db7 Compare April 1, 2026 11:37

dotnet deleted a comment from MauiBot Apr 1, 2026

committed the windows snapshot

0807361

Resolved the gate failures

39a41f2

MauiBot added the s/agent-fix-win AI found a better alternative fix than the PR label Apr 2, 2026

kubaflo changed the base branch from main to inflight/current April 9, 2026 21:17

kubaflo merged commit a49bd0f into dotnet:inflight/current Apr 9, 2026
82 of 88 checks passed

github-actions Bot locked and limited conversation to collaborators May 10, 2026

kubaflo added s/agent-gate-failed AI could not verify tests catch the bug s/agent-suggestions-implemented Maintainer applies when PR author adopts agent's recommendation labels May 20, 2026

Conversation

Shalini-Ashokan commented Feb 9, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Issue Details

Root Cause

Description of Change

Issues Fixed

Output ScreenShot

Uh oh!

sheiksyedm commented Feb 10, 2026

Uh oh!

azure-pipelines Bot commented Feb 10, 2026

Uh oh!

sheiksyedm commented Feb 18, 2026

Uh oh!

github-actions Bot commented Feb 27, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

Copilot AI left a comment

Choose a reason for hiding this comment

Pull request overview

Reviewed changes

Uh oh!

Uh oh!

Uh oh!

Uh oh!

Uh oh!

kubaflo left a comment

Choose a reason for hiding this comment

Uh oh!

sheiksyedm commented Mar 31, 2026 • edited by jfversluis Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

azure-pipelines Bot commented Mar 31, 2026

Uh oh!

jfversluis commented Apr 1, 2026

Uh oh!

azure-pipelines Bot commented Apr 1, 2026

Uh oh!

MauiBot commented Apr 1, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🚦 Gate - Test Before and After Fix

Gate Result: ❌ FAILED

Uh oh!

MauiBot commented Apr 1, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

🤖 AI Summary

Key Findings

Fix Candidates

Fix Candidates

Cross-Pollination

⚠️ Final Recommendation: REQUEST CHANGES

Phase Status

Summary

Root Cause

Fix Quality

Required Changes

Uh oh!

Shalini-Ashokan commented Apr 2, 2026

🤖 AI Summary

Uh oh!

azure-pipelines Bot commented Apr 9, 2026

Uh oh!

Uh oh!

Reviewers

Assignees

Labels

Projects

Milestone

Development

Uh oh!

7 participants

Shalini-Ashokan commented Feb 9, 2026 •

edited

Loading

github-actions Bot commented Feb 27, 2026 •

edited

Loading

sheiksyedm commented Mar 31, 2026 •

edited by jfversluis

Loading

MauiBot commented Apr 1, 2026 •

edited

Loading

MauiBot commented Apr 1, 2026 •

edited

Loading