通过今天的日期，获得本周，本月，上月，本年的开始结束日期

//获取本周 本月 本年的 开始结束日期

- (void)getMonthBeginAndEndWith:(NSDate *)newDate{

    if (newDate == nil) {

        newDate = [NSDate date];

    }

    double interval = 0;

    NSDate *beginDate = nil;

    NSDate *endDate = nil;

    

    NSCalendar *calendar = [NSCalendar currentCalendar];

    [calendar setFirstWeekday:2];//设定周一为周首日

    BOOL ok = [calendar rangeOfUnit:NSMonthCalendarUnit startDate:&beginDate interval:&interval forDate:newDate];

//分别修改为 NSDayCalendarUnit NSWeekCalendarUnit NSYearCalendarUnit 

    if (ok) {

        endDate = [beginDate dateByAddingTimeInterval:interval-1];

    }else {

        return;

    }

    NSDateFormatter *myDateFormatter = [[NSDateFormatter alloc] init];

    [myDateFormatter setDateFormat:@"yyyy.MM.dd"];

    NSString *beginString = [myDateFormatter stringFromDate:beginDate];

    NSString *endString = [myDateFormatter stringFromDate:endDate];

       

Nsstring * str = [NSString stringWithFormat:@"%@-%@",beginString,endString];

Nslog(@"%@",str);// 年 月 周  的开始结束日期；

}

 

 

// 获得当前日期的上个月的日期

- (void)getBeformouthData

{

    NSInteger year,month,day;

    NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

    NSDate *now = [NSDate date];;

    NSDateComponents *comps = [[NSDateComponents alloc] init];

    NSInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit |

    NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;

    

    comps = [calendar components:unitFlags fromDate:now];

    year = [comps year];

    month = [comps month];

    day = [comps day];

    

    

    NSLog(@"现在是:%d年%d月%d日 ",year,month,day);

    //   month获取现在的月份，然后 判断是上个月份是否为12月

    if (month!=1) {

        //       如果mouth!=1,那么上个月月初为1号，年份不变

        NSLog(@"上个月月初:%d-%d-1 ",year,month-1);

        //        处理上个月份为2月的特殊情况，

        if (month!=3) {

            //            如果上个月的月份为 4  6  9  11 月份，他们月末是30号

            if (month == 5 || month==7 || month ==10 || month ==12) {

                NSLog(@"上个月月末:%d-%d-30 ",year,month-1);

            }

            else {

                NSLog(@"上个月月末:%d-%d-31 ",year,month-1);

            }

        }

        //        如果本月是3月份，上个月为为2月份，闰年2月月末29天，非闰年28天

        else {

            if ((year%4==0 && year%100!=0) || year%400==0) {

                NSLog(@"上个月月末:%d-%d-29 ",year,month-1);

            }

            else {

                NSLog(@"上个月月末:%d-%d-28 ",year,month-1);

            }

        }

        

    }

    //    如果当前月份是1月，上个月份就是12月  year-1,month=12

    else {

        NSLog(@"上个月月初为 %d-12-1",year-1);

        NSLog(@"上个月月末为 %d-12-31",year-1);

    }

}

 

//获取当前日期的上周一和上周日的时间

-(NSString *)getWeekTime

{

    NSDate *nowDate = [NSDate date];

    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSDateComponents *comp = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSWeekdayCalendarUnit | NSDayCalendarUnit fromDate:nowDate];

    

    //获取今天周几

    NSInteger weekDay = [comp weekday]-1;

    

    //获取今天是几号

    NSInteger day = [comp day];

    NSLog(@"今天周 %d ==========今天%d号========",weekDay,day);

    

    

    //计算当前日期和本周的周一和周日相差天数

    long firstOffset,lastOffset;

    if(weekDay == 1)

    {

        firstOffset = -6;

        lastOffset = 0;

    }else{

        firstOffset = [calendar firstWeekday] - weekDay-7 ;

        lastOffset =  -weekDay;

    }

    

    NSLog(@"firstOffset %ld=======last %ld",firstOffset,lastOffset);

    

    //在当前日期基础上加上差的天数

    NSDateComponents *firstDayComp = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit  fromDate:nowDate];

    [firstDayComp setDay:day + firstOffset];

    NSDate *firstDayOfWeek = [calendar dateFromComponents:firstDayComp];

    

    NSDateComponents *lastDayComp = [calendar components:NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit   fromDate:nowDate];

    [lastDayComp setDay:day + lastOffset];

    NSDate *lastDayOfWeek = [calendar dateFromComponents:lastDayComp];

    

    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];

    [formatter setDateFormat:@"yyyy-MM-dd"];

    NSString *firstDay = [formatter stringFromDate:firstDayOfWeek];

    NSString *lastDay = [formatter stringFromDate:lastDayOfWeek];

    NSLog(@"%@=======%@",firstDay,lastDay);

    

    //上周的周一 和周日日期

    NSString *dateStr = [NSString stringWithFormat:@"%@%@",firstDay,lastDay];

    

    NSLog(@"date=======%@",dateStr);

    

    /**

     *  firstDay 本周周一

        lastDay 本周周末

     */

    

    return dateStr;

}

    

    NSTimeInterval secondsPerDay = 24 * 60 * 60; 

    //昨天时间

    NSDate *yesterday = [[NSDate alloc] initWithTimeIntervalSinceNow:-secondsPerDay];

    NSString * yestodayStr = [[NSString stringWithFormat:@"%@",yesterday] substringToIndex:10];

    //前天时间

    NSDate *beforeyesterday = [[NSDate alloc] initWithTimeIntervalSinceNow:-secondsPerDay*2];

    NSString * beforeyesterdayStr = [[NSString stringWithFormat:@"%@",beforeyesterday] substringToIndex:10];