title: How can I 'add' two NSLayoutDimensions?
body: <p>Adding two <code>NSLayoutDimension</code> objects doesn't really make sense, but I'm trying to set the height of a container view to the height of two subviews with dynamic heights.</p>
  
  <p>Here's a visual representation of what I'm trying to do, where <code>dynamic view 1</code> and <code>dynamic view 2</code> both have dynamic heights, and the container view sizes according to the sizes of the two dynamic views.</p>
  
  <pre><code> ----------------
  |                |
  | dynamic view 1 |
  |                |
  |                |
  | dynamic view 2 |
  |                |
   ----------------
  </code></pre>
  
  <p>Programmatically, something along the lines of:</p>
  
  <pre><code>heightAnchor.constraint(greaterThanOrEqualTo: dynamicView1.heightAnchor + dynamicView2.heightAnchor).isActive = true
  </code></pre>
  
  <p>But this obviously returns an error. What's the best way to set up these constraints?</p>