title: iOS 5 - Capture the return value from a method being called asynchronously
body: <p>I have a method, fetchFromWeb, that returns an object. I want to call this method asynchronously from GCD. Can someone explain how I would capture the return value from a method being called asynchronously?</p>
  
  <p><strong>Or</strong>, should I set the object value and then set up some sort of notification and not explicitly get the return value from this method at all?</p>
  
  <p>Here is what I have and thanks!</p>
  
  <pre><code>        dispatch_async(kBGQueue, ^{
  
  
              NSData *data = [NSData dataWithContentsOfURL:kURL];
              [self performSelectorOnMainThread:@selector(fetchFromWeb:) 
                                     withObject:data 
                                  waitUntilDone:YES];
  
              //Need to get the return value from method fetchFromWeb in selector....
  
          });
  </code></pre>