IOS 计算本周的起至日期

unsigned units=NSMonthCalendarUnit|NSDayCalendarUnit|NSYearCalendarUnit|NSWeekdayCalendarUnit;        NSCalendar *mycal=[[NSCalendar alloc]initWithCalendarIdentifier:NSGregorianCalendar];
    NSDate *now=[NSDate date];
    NSDateComponents *comp =[mycal components:units fromDate:now];
    NSInteger month=[comp month];
    NSInteger year =[comp year];
    NSInteger day=[comp day];
    NSCalendar *gregorian = [NSCalendar currentCalendar];
    NSDateComponents *dateComps = [gregorian components:NSWeekdayCalendarUnit fromDate:now];
    int daycount = [dateComps weekday] - ;
    NSDate *weekdaybegin=[now addTimeInterval:-daycount***];
    NSDate *weekdayend  =[now  addTimeInterval:(-daycount)***];
    NSDateFormatter *df1=[[NSDateFormatter alloc]init];
    NSLocale *mylocal=[[NSLocale alloc]initWithLocaleIdentifier:@"zh_CN"];
    [df1 setLocale:mylocal];
    [df1 setDateFormat:@"YYYY-MM-d"];

    now=weekdaybegin;
    comp=[mycal components:units fromDate:now];
    month=[comp month];
    year =[comp year];
    day=[comp day];
    NSString *date1=[[NSString alloc]initWithFormat:@"%d-%02d-%02d",year,month,day];//所要求的周一的日期
    now=weekdayend;
    comp=[mycal components:units fromDate:now];
    month=[comp month];
    year =[comp year];
    day=[comp day];
    NSString *date2=[[NSString alloc]initWithFormat:@"%d-%02d-%02d",year,month,day];//所要求的周日的日期