Is it possible to have an update for an option to force it to use gregorian calendar or any calendar?

[sfukuyoshi]

I've tried editing the commented part to

gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
df = [[NSDateFormatter alloc] init];
df.calendar = gregorian;

and it works forcing it to Gregorian. Is it possible to have an option at your end? Thank you.