title: UITableViewCell's contentView gets unwanted "height==44" constraint
body: <p>I'm creating my UI entirely in code and using Masonry to constrain the cell's content view's subviews to the appropriate height. I'm using</p>
  
  <pre><code>[cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height
  </code></pre>
  
  <p>on iOS 7 for the row height, while iOS 8 handles it automatically.</p>
  
  <p>Everything looks exactly as it should on screen, but in the console I get trainloads of warnings for conflicting constraints, which all seem to be caused by an unasked and unnecessary height constraint on the cell's content view (e.g. <code>&lt;NSLayoutConstraint UITableViewCellContentView.height == 44&gt;</code>).</p>
  
  <p>On iOS 8 I'm setting the table view's <code>rowHeight</code> as <code>UITableViewAutomaticDimension</code> (effectively <code>-1</code>) but still I get this constraint. I'm only adding constraints between the content view and its own subviews, so no constraints between the content view and the cell itself.</p>
  
  <p>Any idea where this constraint comes from and how to make it go away?</p>
  
  <p><strong>Edit:</strong> Now I actually found a "solution" of sorts – initially setting the content view's frame to something ridiculous, like <code>CGRectMake(0, 0, 99999, 99999)</code>, before adding subviews or constraints, seems to make the warnings go away. But this doesn't exactly smell like the right way to do it, so can anyone tell of a better approach?</p>