title: AFNetworkActivityIndicatorManager doesn't decrement since table cell recycling cancels image request
body: <p>I'm using <code>UIImageView+AFNetworking:setImageWithURLRequest</code> to load images into table view cells. It's working great and I tried using <code>AFNetworkActivityIndicatorManager</code> as in the example below to display the activity indicator while the images are loading.</p>
  
  <pre class="lang-c prettyprint-override"><code>[[AFNetworkActivityIndicatorManager sharedManager] incrementActivityCount]; 
  [imageView setImageWithURLRequest:request placeholderImage:[UIImage imageNamed:placeholder]
    success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
      [[AFNetworkActivityIndicatorManager sharedManager] decrementActivityCount];
    } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
      [[AFNetworkActivityIndicatorManager sharedManager] decrementActivityCount];
    }
  ];
  </code></pre>
  
  <p>The problem I've run into is when scrolling quickly through the table view AFNetworking cancels certain requests and the <code>AFNetworkActivityIndicatorManager</code> never gets decremented. Canceling requests does keep things fast and appears to be by design:</p>
  
  <blockquote>
    <p>"As table view cells are recycled, for instance, setting a new image URL will automatically cancel the previous request." <a href="https://github.com/AFNetworking/AFNetworking/wiki/Introduction-to-AFNetworking" rel="nofollow">https://github.com/AFNetworking/AFNetworking/wiki/Introduction-to-AFNetworking</a></p>
  </blockquote>
  
  <p>Is there a way to detect the cancellation so I can decrement the <code>AFNetworkActivityIndicatorManager</code> or is there a better way to make sure the requests and activity indicator stay in sync?</p>
  
  <p>Thanks!</p>