title: Swift - NSURL fileURLWithPath not unwrapped?
body: <p>Pretty simple one: I'm getting <code>"Value of optional type 'NSURL?' not unwrapped."</code> on these two lines, which I'm trying to translate from one of my existing Objective-C apps:</p>
  
  <pre><code>func urlForScene(sceneID:Scene) -&gt; NSURL {
      var filename:NSString = "Whatever"
      let path = NSBundle.mainBundle().pathForResource(filename, ofType: "m4a")
      return NSURL.fileURLWithPath(path)
  } 
  </code></pre>
  
  <p>I assume this is probably something blindingly simple to do with the possibility of the <code>path</code> being nil, but I've not found any other questions which let me know what I should be doing here. Apologies if it's a stupid question.</p>
  
  <p>If the <code>NSURL</code> isn't unwrapped, should I unwrap it? Do I need to call <code>fileURLWithPath:</code> differently?</p>
  
  <p>Thanks in advance.</p>