title: How to arrange UIControls relatively
body: <p>I have buttons, labels, etc. in a view. Some elements have no height so I want to set the required height if a button is clicked. No problems so far.<br>
  I want the following elements sliding down and arranging themselves new. I have tried a <code>FlowLayoutController</code> and <code>Auto Layout Constraints</code> but both didn't fulfill my requirements.</p>
  
  <p>The only way I see is to calculate all elements and arrange them programmatically when one item is added or resized.</p>
  
  <p>Is there any other way?</p>