title: How to access from viewController another viewController in Swift 3
body: <p>i need to know how access another viewController from specific viewController.</p>
  
  <p>it's my code</p>
  
  <pre><code>class TabViewController: UITabBarController, UITabBarControllerDelegate  {
  
  var timeLineViewController : TimeineViewController = TimeineViewController()
  
  override func viewDidLoad() {
      super.viewDidLoad()
      timeLineViewController.postList.alpha = 1.0
      // Do any additional setup after loading the view.
  }
  
  override func didReceiveMemoryWarning() {
      super.didReceiveMemoryWarning()
      // Dispose of any resources that can be recreated.
  }
  
   }
  </code></pre>