title: `NSBundle.mainBundle().URLForResource` always returns `nil`
body: <p>I am new to Swift and am using Xcode 6.</p>
  
  <p>I am attempting to read data from the app's <code>plist</code> file, but it is not working.</p>
  
  <p>The <code>data.plist</code> file is included in Xcode's <code>Supporting Files</code> group. </p>
  
  <p>I am using the code below:  </p>
  
  <pre><code>var dataList = NSDictionary(contentsOfURL:NSBundle.mainBundle().URLForResource("data", withExtension:"plist"))
  </code></pre>
  
  <p>however the NSURL:</p>
  
  <pre><code>NSBundle.mainBundle().URLForResource("data", withExtension:"plist")
  </code></pre>
  
  <p>always returns <code>nil</code>.</p>
  
  <p>I don't know what is wrong.</p>