iOS localization for unsupported languages

Question

I want to offer a “Nynorsk localization” option for my app. In the device settings there is no such option, but it looks like iOS actually supports this language, since availableLocaleIdentifiers do contain nn:

kCFLocaleCountryCodeKey = NO;
kCFLocaleLanguageCodeKey = nn;

So I'm confused, is Norwegian Nynorsk supported or not? It's not among device's international languages, but it is among availableLocaleIdentifiers.

I know there are some ways to make custom ‘localizable strings’ work, but so far I did not find a way to make iOS return proper strings for instance for system buttons (Delete button for UITableViewCell, UIBarButtonItem-s from initWithBarButtonSystemItem:target:action, etc).
So the question is if there is a way to indicate a locale for system controls.

Answer 1

Translating iOS app to unsupported/non-standard languages

Choosing localization for unsupported languages

http://applingua.com/supporting-unsupported-languages-in-ios/