计算某一天距离今天多少天，多少小时，多少分钟

- (NSString *)intervalSinceNow: (NSString *) theDate
{
    NSString *timeString=@"";
 
    NSDateFormatter *format=[[NSDateFormatter alloc] init];
    [format setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *fromdate=[format dateFromString:theDate];
    NSTimeZone *fromzone = [NSTimeZone systemTimeZone];
    NSInteger frominterval = [fromzone secondsFromGMTForDate: fromdate];
    NSDate *fromDate = [fromdate  dateByAddingTimeInterval: frominterval];
 
    //获取当前时间
    NSDate *adate = [NSDate date];
    NSTimeZone *zone = [NSTimeZone systemTimeZone];
    NSInteger interval = [zone secondsFromGMTForDate: adate];
    NSDate *localeDate = [adate  dateByAddingTimeInterval: interval];
     
    double intervalTime = [fromDate timeIntervalSinceReferenceDate] - [localeDate timeIntervalSinceReferenceDate];
    long lTime = fabs((long)intervalTime);
    NSInteger iSeconds =  lTime % 60;
    NSInteger iMinutes = (lTime / 60) % 60;
    NSInteger iHours = fabs(lTime/3600);
    NSInteger iDays = lTime/60/60/24;
    NSInteger iMonth =lTime/60/60/24/12;
    NSInteger iYears = lTime/60/60/24/384;
     
     
    NSLog(@"相差%d年%d月 或者 %d日%d时%d分%d秒", iYears,iMonth,iDays,iHours,iMinutes,iSeconds);
     
     
    if (iHours<1 && iMinutes>0)
    {
        timeString=[NSString stringWithFormat:@"%d分",iMinutes];
         
    }else if (iHours>0&&iDays<1 && iMinutes>0) {
        timeString=[NSString stringWithFormat:@"%d时%d分",iHours,iMinutes];
    }
    else if (iHours>0&&iDays<1) {
        timeString=[NSString stringWithFormat:@"%d时",iHours];
    }else if (iDays>0 && iHours>0)
    {
        timeString=[NSString stringWithFormat:@"%d天%d时",iDays,iHours];
    }
   else if (iDays>0)
    {
        timeString=[NSString stringWithFormat:@"%d天",iDays];
    }
    return timeString;
}