// 某年某月的天数- (NSInteger)dayCount:(NSInteger)years{    NSInteger count = 0;    for (int i = 1; i <= 12; i++) {        if (2 == i) {            if((years % 4 == 0 && years % 100!=0) || years % 400 == 0) //是闰年            {                count = 29;            }            else            {                count = 28;            }                    }else if (4 == i || 6 == i || 9 == i || 11 == i){            count = 30;        }else{            count = 31;        }    }    return count;}

// 某天的星期- (NSString * )whichWeek:(NSString *)dateStr{    NSCalendar *calendar = [NSCalendar currentCalendar];    NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];    [inputFormatter setDateFormat:@"yyyy-MM-dd"];    NSDate* inputDate = [inputFormatter dateFromString:dateStr];        NSDateComponents *dateComps = [calendar components:NSCalendarUnitWeekday fromDate:inputDate];        NSInteger weekDay = dateComps.weekday;        switch (weekDay) {        case 1:            return @"星期日";            break;        case 2:            return @"星期一";            break;        case 3:            return @"星期二";            break;        case 4:            return @"星期三";            break;        case 5:            return @"星期四";            break;        case 6:            return @"星期五";            break;        case 7:            return @"星期六";            break;        default:            return @"";            break;    }}