Yay. In iOS 9 you may have noticed some language related issues. All my Instagram push notifications are in German instead of English, for example. After a similar problem appeared in an app we developed, I did some googling and found this technical note, which states:

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

TL;DR: NSLocale.preferredLanguages() now returns en-US instead of en. Update your code if you check for isEqualToString:@"en".