iOS 计算某个月的天数 计算某天的星期

// 某年某月的天数
- (NSInteger)dayCount:(NSInteger)years
{
    NSInteger count = ;
    for (int i = ; i <= ; i++) {
        if ( == i) {
            if((years %  ==  && years % !=) || years %  == ) //是闰年
            {
                count = ;
            }
            else
            {
                count = ;
            }

        }else if ( == i ||  == i ||  == i ||  == i){
            count = ;
        }else{
            count = ;
        }
    }
    return count;
}

// 某天的星期
- (NSString * )whichWeek:(NSString *)dateStr
{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
    [inputFormatter setDateFormat:@"yyyyMMdd"];
    NSDate* inputDate = [inputFormatter dateFromString:dateStr];

    NSDateComponents *dateComps = [calendar components:NSCalendarUnitWeekday fromDate:inputDate];

    NSInteger weekDay = dateComps.weekday;

    switch (weekDay) {
        case :
            return @"星期日";
            break;
        case :
            return @"星期一";
            break;
        case :
            return @"星期二";
            break;
        case :
            return @"星期三";
            break;
        case :
            return @"星期四";
            break;
        case :
            return @"星期五";
            break;
        case :
            return @"星期六";
            break;
        default:
            return @"";
            break;
    }
}