給定一個時間，計算距離當前時間的時間差

NSString *bill_timeStr=@"2016-08-11 12:12:47";

NSString *str1=[self intervalSinceNow:bill_timeStr];

調用方法

- (NSString *)intervalSinceNow: (NSString *) theDate
{
    NSArray *timeArray=[theDate componentsSeparatedByString:@"."];
    theDate=[timeArray objectAtIndex:0];
    NSDateFormatter *date=[[NSDateFormatter alloc] init];
    [date setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *d=[date dateFromString:theDate];
    NSTimeInterval late=[d timeIntervalSince1970]*1;
    NSDate* dat = [NSDate date];
    NSTimeInterval now=[dat timeIntervalSince1970]*1;
    NSString *timeString=@"";
    NSTimeInterval cha=fabs(late-now);
    if (cha/3600<1) {
        timeString = [NSString stringWithFormat:@"%f", cha/60];
        timeString = [timeString substringToIndex:timeString.length-7];
        timeString=[NSString stringWithFormat:@"%@分", timeString];
    }
    if (cha/3600>1&&cha/86400<1) {
        timeString = [NSString stringWithFormat:@"%f", cha/3600];
        timeString = [timeString substringToIndex:timeString.length-7];
        double x;
        x=[timeString doubleValue];
        double y;
        y=cha-x*3600;
        NSString *str1=[NSString stringWithFormat:@"%f", y/60];
        str1 = [str1 substringToIndex:str1.length-7];
        timeString=[NSString stringWithFormat:@"%@時%@分", timeString,str1];
    }
    if (cha/86400>1)
    {
        timeString = [NSString stringWithFormat:@"%f", cha/86400];
        timeString = [timeString substringToIndex:timeString.length-7];
        double x;
        x=[timeString doubleValue];
        double y;
        y=cha-x*86400;
        NSString *str1=[NSString stringWithFormat:@"%f", y/3600];
        str1 = [str1 substringToIndex:str1.length-7];
        double w;
        w=[str1 doubleValue];
        double e;
        e=y-w*3600;
        NSString *str2=[NSString stringWithFormat:@"%f", e/60];
        str2 = [str2 substringToIndex:str2.length-7];
        timeString=[NSString stringWithFormat:@"%@天%@時%@分", timeString,str1,str2];
    }
    return timeString;
}