title: Call main view controller from container view controller
body: <p>I have a container view controller with its own view controller class and some UI components. Some events of this container view controller needs to call the main view controller. I'm not able to find how to do it.</p>
  
  <pre><code>class mainViewController :UIViewController {
        var containerView:UIView!
  }
  
  
  class MyContainerView:UIViewController {
       @IBAction func buttonClick(sender:UIButton){
           // change mainViewController background for example
        }
  }
  </code></pre>