NSCalendar*calendar = [[NSCalendar alloc]initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents*comps = [[NSDateComponents alloc]init];
NSInteger unitFlags =NSCalendarUnitWeekday;
/*-----这里因为我只判断是周几,所以只添加了NSCalendarUnitWeekday,如果需要判断年月日的话,就需要添加NSCalendarUnitYear等,具体格式是
NSInteger unitFlags =NSCalendarUnitWeekday|NSCalendarUnitYear ;
-------*/
NSDate*now =[NSDate date];
comps = [calendar components:unitFlags fromDate:now];
NSLog(@"-----------weekday is %d",[comps weekday]);//周日是1,周一是2...
