[BUG] MathExpressionConverter not working correctly on ios for version 11.0.0 or higher

[Glomby]

Is there an existing issue for this?

• I have searched the existing issues

Did you read the "Reporting a bug" section on Contributing file?

• I have read the "Reporting a bug" section on Contributing file: https://github.com/CommunityToolkit/Maui/blob/main/CONTRIBUTING.md#reporting-a-bug

Current Behavior

I use a MathExpressionConverter with "ConverterParameter='x*-0.9'". The result is used to translate an element on the Y-Axis by 90% of its height.

This works as expected on Android and on iOS for MCT Version 10.0.0 but for version 11.0.0 or higher it only works in Android correctly. On ios it is definitly doing something but not what the MathExpression says. if you just use the expression 'x' it moves the element by its full height to the top. Also some math operations seems to also work.

Expected Behavior

I expect it to do the same on android and ios under version 9.0.0, 10.0.0 or 11.0.0 (and higher versions). The math was never changed by me.

Steps To Reproduce

1. Open the test solution and run the app on an iphone simulator or real device. I tested it myself on a real Iphone X with ios 16.7 and a simulator iphone 15 Pro with ios 17.4.
2. Observe the ContentPage.
3. Change the Nuget version of the community Toolkit to 10.0.0 and observe again. This is the expected behavior.
4. Repeat the above on android and the page should look the same on MCT 10.0.0 or 11.0.0 (including 11.2.0)

Link to public reproduction project repository

https://github.com/Glomby/MathExpressionTest

Environment

- .NET MAUI CommunityToolkit: 11.2.0
- OS: Windows 11 Build 24H2
- .NET MAUI: 9.0.70

Anything else?

This is what you should see. The First image is with MCT 11.2.0 and the top bar has been moved completely out of frame. The second image with version 10.0.0 is how it should look like and how it looks like on android no matter which version of MCT, this includes 9.0.0. But the newest version where this works is 10.0.0

[stephenquan]

Could it be that CultureInfo.CurrentCulture is set to a non-English culture? i.e. troubleshooting (or workaround) by setting CultureInfo.CurrentCulture = new CultureInfo("en-US").

[Glomby]

Yes setting the culture to en-US does fix this. I had it set to de-DE. Changing the simulator phone to english only chamges the culture to en-DE which also causes this issue.

However this is not a workaround for my app since I am supporting multiple languages and have it change cultures depending on the OS. The default culture however is set to en-US.

Right now my workaround is to keep MCT on version 10.0.0, but I would defenitly mark this as a bug because MathExpressions just like other XAML code or C# code should not be affected by the culture settings, that should be front-end only.

[Glomby]

This issue has me still holding on to Community Toolkit 10.0.0.

Anything higher and my math expressions are breaking in my app for any other language other than english.

Is there anything else I am missing to make this work in the newer versions of the toolkit?

[stephenquan]

I believe the following PR will resolve your issues: #2722