iOS 计算时间差（笔记）

#pragma mark - 利用时间戳来准确计算某个时间点具现在的时间差

- (NSString *)intervalSinceNow: (NSString *) theDate

{

    

    NSDateFormatter *date=[[NSDateFormatteralloc] init];

    [date setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

   NSDate *d=[date dateFromString:theDate];

    

    NSTimeInterval late=[dtimeIntervalSince1970]*1;

    

    

    NSDate* dat = [NSDatedateWithTimeIntervalSinceNow:0];

    NSTimeInterval now=[dattimeIntervalSince1970]*1;

   NSString *timeString=@"";

    

   NSTimeInterval cha=now-late;

    

   if (cha/3600<1) {

        timeString = [NSStringstringWithFormat:@"%f", cha/60];

        timeString = [timeStringsubstringToIndex:timeString.length-7];

        timeString=[NSStringstringWithFormat:@"%@分钟前", timeString];

        

    }

   if (cha/3600>1&&cha/86400<1) {

        timeString = [NSStringstringWithFormat:@"%f", cha/3600];

        timeString = [timeStringsubstringToIndex:timeString.length-7];

        timeString=[NSStringstringWithFormat:@"%@小时前", timeString];

    }

   if (cha/86400>1)

    {

        timeString = [NSStringstringWithFormat:@"%f", cha/86400];

        timeString = [timeStringsubstringToIndex:timeString.length-7];

        timeString=[NSStringstringWithFormat:@"%@天前", timeString];

        

    }

   return timeString;

}