title: ARC forbids explicit message send of 'retain' issue
body: <p>I'm using this very simple code from the Apple Guide:</p>
  
  <pre><code>NSMutableData *receivedData;
  
  // Create the request.
  NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.apple.com/"]
                          cachePolicy:NSURLRequestUseProtocolCachePolicy
                      timeoutInterval:60.0];
  // create the connection with the request
  // and start loading the data
  NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
  if (theConnection) {
      // Create the NSMutableData to hold the received data.
      // receivedData is an instance variable declared elsewhere.
      receivedData = [[NSMutableData data] retain];
  } else {
      // Inform the user that the connection failed.
  }
  </code></pre>
  
  <p>But for the line <code>receivedData = [[NSMutableData data] retain];</code> Xcode gives me an error: <code>PushController.m:72:25: ARC forbids explicit message send of 'retain'</code></p>
  
  <p>How to deal with it? I'm using the Xcode 4.4.1</p>