Returns a suffix for a day of the month, eg 1st, 2nd, 2rd, 4th

suffixForDayInDate.m

- (NSString *)suffixForDayInDate:(NSDate *)date{
    NSInteger day = [[[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] components:NSDayCalendarUnit fromDate:date] day];
    if (day >= 11 && day <= 13) {
        return @"th";
    } else if (day % 10 == 1) {
        return @"st";
    } else if (day % 10 == 2) {
        return @"nd";
    } else if (day % 10 == 3) {
        return @"rd";
    } else {
        return @"th";
    }
}