title: 'NSError' is not convertible to 'AutoreleasingUnsafePointer<NSError?>'
body: <p>In my iOS application I need to play sound. I have the following code:</p>
  
  <pre><code>var audioFileLocationUrl = NSBundle.mainBundle().pathForResource("midnight", ofType: "m4a")
  var error: NSError
  var audioPlayer = AVAudioPlayer()
  audioPlayer = AVAudioPlayer(contentsOfURL: audioFileLocationUrl, error: error)
  audioPlayer.prepareToPlay()
  </code></pre>
  
  <p>On line:</p>
  
  <pre><code>audioPlayer = AVAudioPlayer(contentsOfURL: audioFileLocationUrl, error: error)
  </code></pre>
  
  <p>I have error: Could not find overload for 'init' that accepts the supplied arguments</p>