gregorian not supported

[noobAppDeveloper]

in the API it says that this would work, isn't gregorian just a standard by which days are organized?

NSDate *currentDate = [NSDate date];
NSDateComponents *comps = [[NSDateComponents alloc] init];
[comps setDay:10];
NSDate *date = [gregorian dateByAddingComponents:comps toDate:currentDate options:0];
[comps release];

It says that gregorian is undeclared

Edit: This works, it was because the gregorian calendar was not define, I mistakingly thought that it was a built in method. This code works:

NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *weekdayComponents =
[gregorian componentsNSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:today];
NSInteger day = [weekdayComponents day];
NSInteger weekday = [weekdayComponents weekday];