title: iOS: simple animation
body: <p>I want to create a simple animation changing alpha value:</p>
  
  <pre><code>[UIView beginAnimations:nil context:NULL];
  [UIView setAnimationDuration:2];
  [view1 setAlpha:0.00];
  [UIView commitAnimations];
  </code></pre>
  
  <p>Ok in this way I change the alpha value for two seconds and it works fine, but I want this thing:
  When alpha is 0 the animation must should start another time to alpha = 1
  So the animation should be: alpha 0 -> alpha 1 -> alpha 0 -> alpha 1 -> ... and so on with a duration of two seconds.
  Can you help me?</p>
  
  <p>my complete code is</p>
  
  <pre><code>-(IBAction){
  FirstViewController *firstViewController = [[[FirstViewController alloc] init]autorelease];
  [firstViewController.label1 setAlpha:1.00];
  [firstViewController.label2 setAlpha:1.00];
  view = firstViewController.viewFirst; //this is my view and I copy in other view
  [self fadeOut:nil finished:nil context:nil];}
  
  - (void) fadeOut:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
  
  
  [UIView beginAnimations:nil context:NULL];
  [UIView setAnimationDuration:2];
  [UIView  setAnimationDelegate:self];
  [UIView setAnimationDidStopSelector:@selector(fadeIn:finished:context:) ];
  [view setAlpha:0.00];
  [UIView commitAnimations];
  }
  
  - (void) fadeIn:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {
  [UIView beginAnimations:nil context:NULL];
  [UIView setAnimationDuration:2];
  [UIView  setAnimationDelegate:self];
  [UIView setAnimationDidStopSelector:@selector(fadeOut:finished:context:) ];
  [view setAlpha:1.00];
  [UIView commitAnimations];
  }
  </code></pre>