title: Adding Subview creates layout issue
body: <p>I'm programmatically adding a view inside another view like so: </p>
  
  <pre><code>func addViewControllerToSpecificView( view: UIView, controller: UIViewController) {
          controller.willMoveToParentViewController(self)
          view.addSubview(controller.view)           
          self.addChildViewController(controller)
          controller.didMoveToParentViewController(self)
      }
  </code></pre>
  
  <p>The issue is that the parent view ends up being wider than it should be (the width of the screen). </p>
  
  <p>When I don't load the subview using the above method, the positioning is perfect (no extra padding). I have no idea why it's adding an extra ~30px </p>
  
  <p><a href="https://i.stack.imgur.com/fTW1M.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fTW1M.png" alt="enter image description here"></a></p>