icaltimezone_get_builtin_timezones / icaltimezone_get_builtin_timezone_from_tzid not working

Following code returns `NSNULL` in Xcode/iOS simulator:

`    icaltimezone *localTZ = icaltimezone_get_builtin_timezone_from_tzid([[NSTimeZone localTimeZone].name UTF8String]);
`

What do I need to do to make it work?
