+ [NSLocale preferredLanguages] returns different values on iOS compared to OS X

Originator:RadwanAzzouz
Number:rdar://22645639 Date Originated:10-Sep-2015 01:40 PM
Status:Open Resolved:
Product:iOS Product Version:
Classification:iOS Reproducible:Always
 
Summary:
+ [NSLocale preferredLanguages] languages are prefixed by the country code when running on iOS but not when running on OS X.

Please refer to the attached sample projects where we set the text (iOS) and string (OS X) properties to the same value,  "preferredLanguages: \(NSLocale.preferredLanguages())”.

Steps to Reproduce:
1. Build and run the “NSLocale preferredLanguages - iOS” project.
2. Build and run the “NSLocale preferredLanguages - OS X” project.

Expected Results:
+ [NSLocale preferredLanguages] should behave in a similar fashion on both platforms.

Actual Results:
The languages from the iOS project are prefixed with the current locale’s country code ( NSLocale.currentLocale().objectForKey(NSLocaleCountryCode)) while on OS X they are not.

Version:
OS X El Capitan GM, Xcode 7 GM, iOS 9 GM

Notes:
We rely on + [NSLocale preferredLanguages] in our shared code between the Mac and the iOS app. And we expect that + [NSLocale preferredLanguages] does behave in a similar fashion on both platforms.

In iOS 8.4.1 + [NSLocale preferredLanguages] does not append the country code to the preferred language.


Configuration:
OS X El Capitan GM on an Early 2015 13 inch rMBP, iOS 9 GM on an iPhone 6.

Attachments:
'NSLocale preferredLanguages.zip' was successfully uploaded. https://com-agilebits-users.s3.amazonaws.com/rad/NSLocale%20preferredLanguages.zip

Comments

With iOS 9, the results returned by NSLocale.preferredLanguages() can differ from previous releases

With iOS 9, the results returned by NSLocale.preferredLanguages() can differ from previous releases. In iOS 8 and earlier, only certain language, script, and region combinations were returned by this API. However, in iOS 9, more combinations of language, script, and region are permitted.

For example, when a user has configured their iOS device with language set to English and region set to India, NSLocale.preferredLanguages() will now return [ "en-IN" ], instead of [ "en" ]. This allows for smarter language fallbacks; for this user, if an app doesn’t support en-IN as a localization, but does support en-GB, the fallback mechanism will select en-GB instead of en.

Read more at : https://developer.apple.com/library/ios/technotes/tn2418/_index.html#//apple_ref/doc/uid/DTS40016588

By yeradis at Oct. 7, 2015, 10:24 a.m. (reply...)

Hi yeradis,

Thanks so much for taking the time to comment on this rdar :+1:

According to the technical note this is indeed the expected behaviour in iOS 9. However, the problem was originally reported due to the inconsistent results between iOS 9 and OS X El Capitan when using + [NSLocale preferredLanguages] in a shared code base or frameworks. Since NSLocale is a Foundation API, one would expect that such an API would return similar results on both platforms.

Thank you :-D

By RadwanAzzouz at Nov. 6, 2015, 3:27 p.m. (reply...)

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