Create NSString from NSTimeInterval with format HH:MM::SS

stringFromTimeInterval

- (NSString *)stringFromTimeInterval:(NSTimeInterval)interval
{
    NSInteger ti = (NSInteger)interval;
    NSInteger seconds = ti % 60;
    NSInteger minutes = (ti / 60) % 60;
    NSInteger hours = (ti / 3600);
    NSString *time = nil;
    if (hours > 0) {
        time = [NSString stringWithFormat:@"%02i:%02i:%02i", hours, minutes, seconds];
    }
    else {
        time = [NSString stringWithFormat:@"%02i:%02i", minutes, seconds];
    }
    return time;
}