Смена чисел по интервалу в приложении iOS?

@interface MyViewController () {
    NSTimer *timer;
    int seconds;
    ...
} 
@property (weak, nonatomic) IBOutlet UILabel *timerLabel;
@end
...

- (void)viewDidLoad
{
    [super viewDidLoad];
    timer = [NSTimer scheduledTimerWithTimeInterval:1.0f  target:self selector:@selector(updateTimer:) userInfo:nil repeats:YES];
   seconds = 0;
}

- (void)updateTimer:(NSTimer *)theTimer {
   [functions playSound:[NSString stringWithFormat:@"%@",seconds] ofType:@"aac"];
   seconds++;
}