Ios Maui sample app uses Chinese Simplified when Chinese Traditional is set in phone preferences

[Czapek83]

Description

Created new maui project. Created Strings.resx, Strings.zh.resx, Strings.zh-Hans.resx, and Strings.zh-Hant.resx files with below values of SampleText:

On MainPage.xaml added label that will display proper text according to current language:

And now, when setting Iphone Region to "China mainland" and language to "Chinese Traditional", the SampleText is taken from Chinese, Simplified, but should be taken from Chinese, Traditional:

Steps to Reproduce

1. Create new maui project.
2. Create localized strings in Resources (Strings.zh-Hans.resx for Chinese Simplified and Strings.zh-Hant for Chinese Traditional) with different strings in it.
3. Use localized string in one of your screens
4. Change your Iphone region to "China mainland" and language to "Chinese Traditional".
5. Run your application and you can see that Chinese Simplified string is used.

Link to public reproduction project repository

https://github.com/Czapek83/Chinese_LanguageIssue

Version with bug

8.0.21 SR4.1

Is this a regression from previous behavior?

Not sure, did not test other versions

Last version that worked well

Unknown/Other

Affected platforms

iOS

Affected platform versions

IOS 16.7.7, IOS 17.4.1

Did you find any workaround?

Unfortunatelly, not at all.

Relevant log output

No response

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[rolfbjarne]

I can reproduce this.

Adding the following in the managed Main method:

Console.WriteLine ($"CurrentCulture: {Thread.CurrentThread.CurrentCulture.Name}");
Console.WriteLine ($"CurrentUICulture: {Thread.CurrentThread.CurrentUICulture.Name}");
Console.WriteLine ($"NSLocale.CurrentLocale.LocaleIdentifier: {NSLocale.CurrentLocale.LocaleIdentifier}");
Console.WriteLine ($"NSLocale.CurrentLocale.CountryCode: {NSLocale.CurrentLocale.CountryCode}");
Console.WriteLine ($"NSLocale.CurrentLocale.LanguageCode: {NSLocale.CurrentLocale.LanguageCode}");
Console.WriteLine ($"NSLocale.CurrentLocale.ScriptCode: {NSLocale.CurrentLocale.ScriptCode}");

prints:

CurrentCulture: zh-CN
CurrentUICulture: zh-CN
NSLocale.CurrentLocale.LocaleIdentifier: zh-Hant_CN
NSLocale.CurrentLocale.CountryCode: CN
NSLocale.CurrentLocale.LanguageCode: zh
NSLocale.CurrentLocale.ScriptCode: Hant

Debugging a bit it seems we hit this code path:

runtime/src/native/libs/System.Globalization.Native/pal_locale.m

Lines 27 to 30 in 994a410

	if ([currentLocale.languageCode length] > 0 && [currentLocale.countryCode length] > 0)
	{
	localeName = [NSString stringWithFormat:@"%@-%@", currentLocale.languageCode, currentLocale.countryCode];
	}

which means the current (ui) culture is determined using the current locale's LanguageCode-CountryCode (which results in "zh-CN"), not the locale's LocaleIdentifier, nor taking into account the ScriptCode value (which both contain "Hant").

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[tarekgh]

CC @steveisok

[steveisok]

/cc @vitek-karas

[lewing]

cc @mkhamoyan

[vitek-karas]

/cc @matouskozak

[matouskozak]

Can confirm that the issue is reproducible with .NET 8. Works as expected with .NET 9.

[lewing]

Is the issue how we construct the icu locale in net8.0 or the fact that we've potentially removed the required information from the icu bundle we produce for size reasons?

[matouskozak]

Is the issue how we construct the icu locale in net8.0 or the fact that we've potentially removed the required information from the icu bundle we produce for size reasons?

I'm unsure, I have thought that we have full ICU when hybrid globalization is not enabled on .NET 8 (do you know @mkhamoyan ?).

I did some digging and the correct language can be set using [[NSLocale preferredLanguages] objectAtIndex:0] (returns expected zh-Hant-CN).

[mkhamoyan]

@matouskozak We have whitelisted locales for ICU in net8.0 https://github.com/dotnet/icu/blob/dotnet/main/icu-filters/icudt_mobile.json#L8-L194 and I don't see here zh-Hant_CN.
For hybrid mode we do get default locale using preferedLanguages as you mentioned

runtime/src/native/libs/System.Globalization.Native/pal_locale.m

Line 795 in 994a410

return strdup([NSLocale.preferredLanguages[0] UTF8String]);

[sowacx]

Hey, this:

For hybrid mode we do get default locale using preferedLanguages as you mentioned

Is applied only if there are more than 1 preferedLanguages selected. For single one it can be still evaluated as
localeName = [NSString stringWithFormat:@"%@-%@", currentLocale.languageCode, currentLocale.countryCode];

[mkhamoyan]

@sowacx, The check NSLocale.preferredLanguages.count > 0 is verifying the presence of any preferred languages. According to the documentation, the primary language of the device will always be included in the preferred languages list.

[matouskozak]

Fixed in #102748, should be part of next servicing release (8.0.8).