title: IPHONE - fade in and fade out of a UIImageView with different times
body: <p>I would like to do a fade in and out of a UIImageView using different times, let's say, using the following parameters:</p>
  
  <ul>
  <li>t = 0     ... UIImageView's alpha = 0</li>
  <li>t = 0.5s  ... UIImageView's alpha = 0.7</li>
  <li>t = 0.7s  ... UIImageView's alpha = 0</li>
  </ul>
  
  <p>Is this possible to do with CAAnimation or other method?
  How can that be done?</p>
  
  <p>thanks for any help! </p>