title: swift: show animation after returning in ViewController
body: <p>I have first <code>ViewController</code> and second <code>ViewController</code>. When I return to first <code>ViewController</code> from second <code>ViewController</code> after that I want to show buttons in first <code>ViewController</code>. </p>
  
  <p>To returning I use this code:</p>
  
  <pre><code>self.dismiss(animated: true, completion: nil)
  </code></pre>
  
  <p>And this code to show buttons in first <code>ViewController</code></p>
  
  <pre><code>@IBOutlet weak var infoButton: UIButton!
  @IBOutlet weak var nextButton: UIButton!
  
  @IBOutlet weak var infoButtonTopConstraint: NSLayoutConstraint!
  @IBOutlet weak var nextButtonBottomConstraint: NSLayoutConstraint!
  @IBOutlet weak var infoButtonHeightConstraint: NSLayoutConstraint!
  @IBOutlet weak var nextButtonHeightConstraint: NSLayoutConstraint!
  
  override func viewWillAppear(_ animated: Bool) {
      super.viewWillAppear(true)
  
      showButtonAnimation()
      //animaton()
  }
  
  func showButtonAnimation() {
  
      self.infoButtonTopConstraint.constant += self.infoButtonHeightConstraint.constant
      self.nextButtonBottomConstraint.constant -= self.nextButtonHeightConstraint.constant
  
      UIView.animate(withDuration: 1.0, delay: 0.0,
                     options: [], animations: {
                      self.view.layoutIfNeeded()
  
      })
  }
  </code></pre>
  
  <p>But buttons not showing when I return from second <code>ViewController</code>.</p>