How to add language to NSSpellChecker's available languages?
It seems like the NSSpellChecker class has some bugs in it. There already was a discussion about a bug with custom NSSpellChecker servers back in 2008 (which was fixed few months later).
At the moment I suggest you to file a bugreport since your code is correct as the documentation and the compiler says.
Update
There are lots of other bugs regarding the NSSpellChecker class, so it doesn't surprise me, that you just found another one.
- Automatic language detection
- Unexpected return value in
countWordsInString:language: - Crashing application due to
NSSpellCheckerCheckString
Buggy NSSpellChecker it seems...