title: iOS 8 SDK: [UIImage imageNamed:] issue
body: <p>In previous iOS SDK, <code>[UIImage imageNamed:]</code> can determine the image to load automatically without giving the file extension, for example:</p>
  
  <pre><code>[ivTest setImage:[UIImage imageNamed:@"testImage"]];
  </code></pre>
  
  <p>It will search for appropriate image to load (i.e. <code>testImage.jpg</code> &amp; <code>testImage@2x.jpg</code>). But for iOS 8, it sometimes cannot identify the correct image to load, and just returns <code>null</code>.</p>
  
  <p>I have to specify the extension:</p>
  
  <pre><code>[ivTest setImage:[UIImage imageNamed:@"testImage.jpg"]];
  </code></pre>
  
  <p>But this happens only in same rare cases. </p>
  
  <p>Given that I have only the following images in the project:</p>
  
  <ul>
  <li>testImage.jpg</li>
  <li>testImage@2x.jpg</li>
  </ul>
  
  <p>No other images with similar names. How can I prevent this? Should I specify extension for all my <code>imageNamed:</code> ?</p>