The missing NSLocale documentation

+ (NSArray *)preferredLanguages
Return Value
The user's language preference order as an array of NSString objects, each of which is a canonicalized IETF BCP 47 language identifier. This is defined by the user in System Preferences → International → Language.

For your information: this is stored in the gloal domain in the AppleLanguages key.

+ (id)currentLocale
Return Value
The logical locale for the current user. The locale is formed from the settings for the current user’s chosen system locale overlaid with any custom settings the user has specified in System Preferences → International → Formats.
This method may return a retained cached object.


+ (id)autoupdatingCurrentLocale
This one I have not understood how it is supposed to be used. If someone knows, please let us know in the comments.

Now, if what you want is the current language, you should not use either of these methods. Instead you should use something like NSLocalizedString(@"ISOLanguageCode", @"iso language code"). Then you have to define "ISOLanguageCode" = "en"; etc. in all your Localizable.strings files.