title: UIButton flashing animation
body: <p>I was wondering if it was possible to apply a flashing animation to a UIButton. I have searched but only found the code for a pulse animation which changes the size of my UIButton continuously. I instead was thinking about some kind of flashing animation to alert the user he has to press the button. The only approach to the problem  I can think of is by changing the alpha constantly using:</p>
  
  <pre><code>[self setAlpha:0.5]; 
  </code></pre>
  
  <p>...but it won't be as visible as a flashing button.</p>