title: Issue with setImageWithURL AFNetworking success handler
body: <p>Neither the success or failure handler appears to be called when <code>setImageWithURLRequest:</code> is called on my <code>UIImage</code> object. <code>SetImageWithURL</code> does not set my image either. If I use <code>setImageWithURL:</code> <code>placeholder:</code> the placeholder is set but the image from the url never gets set.</p>
  
  <p>Pardon my not posting code sooner. I have tried to use two methods (with <code>AFNetworking</code>) to asynchronously set my image views:</p>
  
  <pre><code>[_imageView setImageWithURL:[NSURL URLWithString:@"path/to/file"]];
  
  [_imageView setImageWithURLRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.example.com/path/to/image.jpg"]] placeholderImage:[UIImage imageNamed:@"your_image_here.jpg"] success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
  NSLog(@"Your image request succeeded!");
  } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {
  NSLog(@"Your image request failed...");
  }];
  </code></pre>
  
  <p>I have tried having these triggered in <code>viewDidLoad</code> but the image view never loads.</p>
  
  <p>After looking through the actual function declaration of <code>setImageWithURLRequest:</code> and it appears that neither the success or failure block is executed when I call it. I've placed <code>NSLogs</code> in the code to give you guys an idea of what happens:</p>
  
  <pre><code>- (void)setImageWithURLRequest:(NSURLRequest *)urlRequest 
        placeholderImage:(UIImage *)placeholderImage 
                 success:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image))success
                 failure:(void (^)(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error))failure
  {
  NSLog(@"Log shows");
  
  [self cancelImageRequestOperation];
  
  NSLog(@"Log shows");
  UIImage *cachedImage = [[[self class] af_sharedImageCache] cachedImageForRequest:urlRequest];
  
  NSLog(@"Log shows");
  
  if (cachedImage) {
  NSLog(@"Log does not show");
  
  self.image = cachedImage;
  self.af_imageRequestOperation = nil;
  
  if (success) {
      success(nil, nil, cachedImage);
      NSLog(@"Log does not show");
  
  }
  } else {
  NSLog(@"Log shows");
  
  self.image = placeholderImage;
  
  AFImageRequestOperation *requestOperation = [[AFImageRequestOperation alloc] initWithRequest:urlRequest];
  [requestOperation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
      if ([[urlRequest URL] isEqual:[[self.af_imageRequestOperation request] URL]]) {
          self.image = responseObject;
          self.af_imageRequestOperation = nil;
          NSLog(@"Log does not show");
      }
  
      if (success) {
          success(operation.request, operation.response, responseObject);
          NSLog(@"Log does not show");
      }
  
      [[[self class] af_sharedImageCache] cacheImage:responseObject forRequest:urlRequest];
  
  
  } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
      if ([[urlRequest URL] isEqual:[[self.af_imageRequestOperation request] URL]]) {
          self.af_imageRequestOperation = nil;
          NSLog(@"Log does not show");
      }
  
      if (failure) {
          failure(operation.request, operation.response, error);
          NSLog(@"Log does not show");
      }
  
  }];
  
  self.af_imageRequestOperation = requestOperation;
  
  [[[self class] af_sharedImageRequestOperationQueue] addOperation:self.af_imageRequestOperation];
  </code></pre>