title: Add Child View Controller to Navigation controller
body: <p>I try add child view controller multiple. i want to add search controller to home controller as child view controller . that's work good hear is my code :</p>
  
  <pre><code>func ShowSearchController() {
  
      let secondViewController:SearchController = SearchController()
      let navController = UINavigationController.init(rootViewController: secondViewController)
      self.navigationController?.addChildViewController(navController)
  
      secondViewController.navigationController?.view.frame = (self.navigationController?.view.frame)!
      secondViewController.view.frame = (self.navigationController?.view.frame)!
      self.navigationController?.view.addSubview(secondViewController.view)
      secondViewController.beginAppearanceTransition(true, animated: true)
  
      UIView.animate(withDuration: 0.2, animations: {
      }, completion: {
        (value: Bool) in
        secondViewController.endAppearanceTransition()
        secondViewController.didMove(toParentViewController: self)
      })
  
    }
  </code></pre>
  
  <p>now i want to show another view controller to search controller. for present second view controller i'm using this method but thats not work. 
  how can add child view controller to navigation controller few times?</p>