title: AFImageRequestOperation returns image that not downloaded competely
body: <pre><code>+[AFImageRequestOperation imageRequestOperationWithRequest:
                                        imageProcessingBlock:
                                                     success:
                                                     failure:]
  </code></pre>
  
  <p>In case of slow internet returns image (PNG particularly) that didn't download completely and failure block, in this situation, is not being called.<br /></p>
  
  <p>How can I check that the image did or didn't download correctly?</p>
  
  <p><strong>Edit:</strong> It doesn't really matter what type of request you will have: image, xml, json or http, there are a probability that file downloading will fail. And as file becomes bigger and internet becomes slower the probability increases.</p>