title: What happens with constraints when a view is removed
body: <p>The question I have is simple but I couldn't find any information in the documentation.</p>
  
  <p>What happens with layout constraints when a view is removed from the view hierarchy (or moved to another view)?</p>
  
  <p>For example, let's have container <code>C</code> with subviews <code>A</code> and <code>B</code>. Container <code>C</code> holds some constraints. Then we call <code>[A removeFromSuperview]</code>. What happens with the constraints for <code>A</code>?</p>
  
  <p>What then happens if we add <code>A</code> to <code>C</code> again?</p>