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.
 
     
    