`NSLocale preferredLanguages` contains "-US" since iOS 9 - ios

Question

We have code like the following to retrieved the user language preference:
NSString *language = [[NSLocale preferredLanguages] firstObject];
Before iOS 8.4, language is "zh-Hans", "de", "ru", "ja" and etc. But since iOS 9, I notice that there is additional three characters "-US" appended to language. For example, "zh-Hans" becomes "zh-Hans-US"
I can find any documentation about this change. I assume that I could do something like the following to workaround this issue.
NSRange range = [language rangeOfString:#"-US"];
if (range.location!=NSNotFound && language.length==range.location+3) {
// If the last 3 chars are "-US", remove it
language = [language substringToIndex:range.location];
}
However, I am not sure whether it is safe to do so. It seems that "-US" is the location where the user is using the app? But this doesn't really make sense because we are in Canada. Has any body from other part of the world tried this?

Answer 1

Apple has started adding regions onto the language locales in iOS 9. Per Apple's docs, it has a fallback mechanism now if no region is specified. If you need to only support some languages, here is how I worked around it, per Apple's docs suggestion:
NSArray<NSString *> *availableLanguages = #[#"en", #"es", #"de", #"ru", #"zh-Hans", #"ja", #"pt"];
self.currentLanguage = [[[NSBundle preferredLocalizationsFromArray:availableLanguages] firstObject] mutableCopy];
This will automatically assign one of the languages in the array based off the User's language settings without having to worry about regions.
Source: Technical Note TN2418

Answer 2

To extract the region I think this is a better solution:
// Format is Lang - Region
NSString *fullString = [[NSLocale preferredLanguages] firstObject];
NSMutableArray *langAndRegion = [NSMutableArray arrayWithArray:[fullString componentsSeparatedByString:#"-"]];
// Region is the last item
NSString *region = [langAndRegion objectAtIndex:langAndRegion.count - 1];
// We remove region
[langAndRegion removeLastObject];
// We recreate array with the lang
NSString *lang = [langAndRegion componentsJoinedByString:#"-"];

Answer 3

Swift 5: Remove region from preferred language
Using Locale.preferredLanguages.first gives you the preferred App language (which can be different than device language for the user).
In order to support the script code and language code (but to remove the region code) I think it is best to create a locale given the preferred language and grab the information we need from there.
if let pref = Locale.preferredLanguages.first {
let locale = Locale(identifier: pref)
let code = [locale.languageCode, locale.scriptCode].compactMap{$0}.joined(separator: "-")
print(code)
}
So first we get the preferred app language, Then create a locale from the language.
To get the language code we create an array with locale.languageCode and the locale.scriptCode (which may be nil), remove any nil values with compactMap and then join the values with a "-".
This should allow support for Simplified Chinese and Traditional, and let Apple handle the region instead of assuming it will always be there.