title: Can't center views in tableHeaderView with auto layout and storyboards
body: <p>I can't center a view that has been placed as a subview of a UITableView's tableHeaderView in a storyboard using auto layout.</p>
  
  <p>In a storyboard, I have a <code>UITableView</code>. I dragged a <code>UIView</code> (the red view) to the top, released, and it created a table header view automatically. I then dragged and dropped another <code>UIView</code> (the yellow view) on top of the table header view, resized, and applied some constraints to ensure it stays centered:</p>
  
  <p><img src="https://i.stack.imgur.com/IyQIR.png" alt="enter image description here"></p>
  
  <p>When I run the app on the simulator, here's what I get:</p>
  
  <p><img src="https://i.stack.imgur.com/tskeE.png" alt="enter image description here"></p>
  
  <p>The yellow view is obviously not centered. However, the "Filter" button at the bottom is.</p>
  
  <p>I know it's tricky to get the height right using auto layout and storyboards and table header views (and you can see that the height of the red view is definitely incorrect), but at this point, I'm just trying to solve for horizontally centering my yellow view. </p>
  
  <p>Am I able to set this all up in my storyboard without having to configure my constraints in code?</p>