UILabel as countdown timer given NSTimeInterval

UILabel with Countdown

-(void) updateCountdown {
    NSTimeInterval timeToClosing = [_deleteDate timeIntervalSinceDate:[NSDate date]];
    
    div_t h = div(timeToClosing, 3600);
    int hours = h.quot;
    div_t m = div(h.rem, 60);
    int minutes = m.quot;
    int seconds = m.rem;
    
    NSString *hoursStr, *minutesStr, *secondsStr;
    if (hours < 10)
        hoursStr = [NSString stringWithFormat:@"0%d", hours];
    else
        hoursStr = [NSString stringWithFormat:@"%d", hours];
    if (minutes < 10)
        minutesStr = [NSString stringWithFormat:@"0%d", minutes];
    else
        minutesStr = [NSString stringWithFormat:@"%d", minutes];
    if (seconds < 10)
        secondsStr = [NSString stringWithFormat:@"0%d", seconds];
    else
        secondsStr = [NSString stringWithFormat:@"%d", seconds];
    
    if (seconds < 0)
        [self dismissButtonTapped];
    else
        self.countdownLabel.text = [NSString stringWithFormat:@"%@:%@:%@", hoursStr, minutesStr, secondsStr];
    if (timeToClosing <= 30) {
        [_switchTimer invalidate];
        _switchTimer = nil;
        [UIView animateWithDuration:0.7
                         animations:^{
                             self.eventEndsLabel.alpha = 0.0f;
                             self.countdownLabel.alpha = 1.0f;
                         }];
    }
}