NSLocale category to get an ISO639.2 language identifier code

Example usage:

[[NSLocale currentLocale] ISO639_2LanguageIdentifier];

This category first gets the value for the NSLocaleLanguageCode key from an NSLocale object and then uses a plist to lookup the corresponding ISO 639.2 language code.

If a language code can not be found, the result of NSLocaleLanguageCode is returned directly.

Don't forget to include the iso639_1_to_iso639_2.plist to your bundle otherwise the category won't work.

The plist is created following this website