+ (NSString *) compareCurrentTime:(NSString *)str
 {
    //把字串轉為NSdate
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
    NSDate *timeDate = [dateFormatter dateFromString:str];
    NSDate *currentDate = [NSDate date];
    NSTimeInterval
 
 timeInterval = [currentDate timeIntervalSinceDate:timeDate];
    long temp = 0;
    NSString *result;
    if (timeInterval/60 < 1) 
    {
        result = [NSString stringWithFormat:@"剛剛"];
    }
    else if((temp = timeInterval/60) <60){
        result = [NSString stringWithFormat:@"%ld分鐘前",temp];
    }
    else
 
 if((temp = temp/60) <24){
        result = [NSString stringWithFormat:@"%ld小時前",temp];
    }
    else if((temp = temp/24) <30){
        result = [NSString stringWithFormat:@"%ld天前",temp];
     }
    else if((temp = temp/30) <12){
        result = [NSString stringWithFormat:@"%ld月前",temp];
     }
    else
 
{
        temp = temp/12;
        result = [NSString stringWithFormat:@"%ld年前",temp];
     }
     return  result;
  }