带有计时器动画的xcode iphone问题

- (void)animateBall
{
    // Animation for ball jumping.
    // This is just going to move it up and down but it\'s something to start

    float duration 1.0f;

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:duration];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationRepeatCount:1];
    [UIView setAnimationRepeatAutoreverses:YES];
    [imageView setTransform:CGAffineTransformMakeTranslation(0, 100.0f)];
    [UIView commitAnimations];
}

- (void)run
{
    [NSTimer scheduledTimerWithTimeInterval:10
                                     target:self 
                                   selector:@selector(animateBall) 
                                   userInfo:nil 
                                    repeats:YES];
}

AnimationDidStopSelector