title: Open native UIViewController in Flutter
body: <p>I have an application I develop in Flutter, and it has one UIViewController that has to be implemented in native IOS (there is no other workaround, it is a must)</p>
  
  <p>I have implemented it, it works according to the first tests, but I'd like to double check if it is okkey by your opinion, as I am not so experienced in Flutter, and I am afraid a bit a <em>make some mess in my app navigation stack that can cause bugs in the future</em>.</p>
  
  <p>So, I have implemented it by MethodChannel. I have a method, that called from 'Flutter side'. I don't paste my MethodChannel related things here, as they are trivial.</p>
  
  <p>In my AppDelegate didFinishLaunchingWithOptions I added this:</p>
  
  <pre><code>let flutterViewController = FlutterViewController()
      self.navigationController = UINavigationController(rootViewController: flutterViewController)
      self.navigationController?.isNavigationBarHidden = true
  
      self.window = UIWindow(frame: UIScreen.main.bounds)
      self.window.rootViewController = self.navigationController
      self.window.makeKeyAndVisible()
  </code></pre>
  
  <p>And my open method like this:</p>
  
  <pre><code>private func openNativeUI(result: FlutterResult) {
          let sb = UIStoryboard(name: "Main", bundle: nil)
          let uiController = sb.instantiateViewController(withIdentifier: "nativeui")
  
          self.navigationController?.pushViewController(uiController, animated: true)
  
          result(true)
      }
  </code></pre>
  
  <p>What do you think?</p>
  
  <p>Any advise is highly appreciated and thank you for your help in advance!</p>