title: Change background from OS X application
body: <p>After mastering iOS apps, I'm trying to develop a simple OS X application but this doesn't seem to be as easy as I'd have expected.</p>
  
  <p>I've made some successful experiences such as adding a button to the XIB and changing its title within the appdelegate.m, or adding a click event handler, well...</p>
  
  <p>The app has the following structure :</p>
  
  <p>Window > View</p>
  
  <p>I'm trying to change the view's background using this :</p>
  
  <pre><code>self.nameOfTheView.layer.backgroundColor = CGColorCreateGenericRGB(255, 0, 0, 0.9);
  </code></pre>
  
  <p>in the <code>- (void)applicationDidFinishLaunching:(NSNotification *)aNotification</code> method but nothing happens.
  What am I doing wrong ?</p>