title: iOS Caching images with AFImageCache doesn't seem to work
body: <p><br />
  I'm trying to cache some images loaded from a URL by using AFImageCache, without success... I'm not sure If i'm doing anything wrong and would love your opinions if you've ever used this library.</p>
  
  <p>I'm getting an image from a NSURLRequest, and then caching it as follows</p>
  
  
  
  <pre><code>UIImage *img; //This image is a png icon returned from the server
  NSData *imgData = UIImagePNGRepresentation(img); // Always checking length to make sure its more than 0, and it is
  
  [[AFImageCache sharedImageCache] cacheImageData: imgData
                                           forURL: myURL
                                        cacheName: @"IconCache"];
  </code></pre>
  
  <p>On the next run, i'll try to check if the image was cached, but will always get <code>nil</code> for some reason.</p>
  
  <pre class="lang-cpp prettyprint-override"><code>UIImage *myIcon = [[AFImageCache sharedImageCache] cachedImageForURL: myURL cacheName: @"IconCache"];
  
  NSLog("%@", myIcon); // output (null)
  </code></pre>
  
  <p>Any ideas or thoughts about this?
  Thanks.</p>