时间格式转换算法: XXXXXX -> XX:XX:XX

- (NSString *)formatterDurationToString:(double)duration

 {

     int secs = (int)duration;

     int hour = secs/3600;

     int minute = (secs % 3600)/60;

     int sec = secs % 60;

     NSString *durationStr;

     if (hour>0)

     {

         durationStr = [NSString stringWithFormat:@"%d:%02d:%02d",hour,minute,sec];

     }

     else

     {

         durationStr = [NSString stringWithFormat:@"%02d:%02d",minute,sec];

     }

     return durationStr;

 }