title: Is it possible to set constraints for root view in XIB?
body: <p>Recently i was following a <a href="https://medium.com/flawless-app-stories/getting-started-with-reusable-frameworks-for-ios-development-f00d74827d11" rel="noreferrer">tutorial</a> to create frameworks in Swift, Where they create reusable visual effect view just like we see in Xcode build success pop up. I was doing the UI step by step where they created a new xib file and dragged and dropped <code>UIVisualEffectView</code> into it. </p>
  
  <p><a href="https://i.stack.imgur.com/mOh3w.png" rel="noreferrer"><img src="https://i.stack.imgur.com/mOh3w.png" alt="Empty UIVisualEffectView without constraints"></a></p>
  
  <p>In the above image we can see that the <code>UIVisualEffectView</code> doesn't contain any constraints. It only has auto resizing masks in size inspector(as expected).</p>
  
  <hr>
  
  <p>But the following image from the tutorial suddenly contains all necessary constraints for it's root view.</p>
  
  <p><a href="https://i.stack.imgur.com/mEO1Y.png" rel="noreferrer"><img src="https://i.stack.imgur.com/mEO1Y.png" alt="UIVisualEffectView with constraints"></a></p>
  
  <p>I'm already aware that we CANNOT, by default set any constraints for the root view. But in the tutorial the author seems to have added constraints for the same. I'm just curious to know if it is possible to do that or am i missing any fundamental idea ?</p>
  
  <p><strong>EDIT:</strong></p>
  
  <p>Constraints for root view.</p>
  
  <p><a href="https://i.stack.imgur.com/SzWbm.png" rel="noreferrer"><img src="https://i.stack.imgur.com/SzWbm.png" alt="UIAfterEffectView constraints"></a></p>