title: UIScreen mirroredScreen property always returns nil
body: <p>I want to present unique content on the external connected display if mirroring is not supported by the device (original iPad) but want to use screen mirroring if it's iPad 2. Now when I try to code this as follows:</p>
  
  <pre><code>if ([UIScreen instancesRespondToSelector:@selector(mirroredScreen)] &amp;&amp; [[UIScreen mainScreen] mirroredScreen] == nil) {
      // Mirroring not supported. Present unique content on external display
  }
  </code></pre>
  
  <p><code>[[UIScreen mainScreen] mirroredScreen]</code> always returns <code>nil</code>.</p>
  
  <p>Am I doing something wrong?</p>