iOS开发 根据日期计算是星期几详解手机开发

 NSDateComponents *_comps = [[NSDateComponents alloc] init]; 
    [_comps setDay:23]; 
    [_comps setMonth:3]; 
    [_comps setYear:2014]; 
    NSCalendar *gregorian = [[NSCalendar alloc] 
                             initWithCalendarIdentifier:NSGregorianCalendar]; 
    NSDate *_date = [gregorian dateFromComponents:_comps]; 
    NSDateComponents *weekdayComponents = 
    [gregorian components:NSWeekdayCalendarUnit fromDate:_date]; 
    int _weekday = [weekdayComponents weekday]; 
    NSLog(@"_weekday::%d",_weekday);