title: systemLayoutSizeFittingSize: on UILabel not behaving like expected
body: <p>I found a different behavior of the <code>systemLayoutSizeFittingSize:</code> method then i expected.</p>
  
  <p>Here is an code snipped for a swift Playground which demonstrates the behavior but its the same in Objective-C:</p>
  
  <pre><code>import UIKit
  import Foundation
  
  var label = UILabel()
  
  label.text = "This is a Test Label Text"
  
  label.numberOfLines = 0
  
  label.font = UIFont.preferredFontForTextStyle(UIFontTextStyleBody)
  
  label.preferredMaxLayoutWidth = 40
  
  let layoutSize = label.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize)
  
  let intrinsicSize = label.intrinsicContentSize()
  </code></pre>
  
  <p>I would have expected that <code>layoutSize</code> and <code>intrinsicSize</code> are the same.</p>
  
  <p>But in this case <code>layoutSize</code> is <code>(w 173, h 20)</code> and <code>intrinsicSize</code> is <code>(w 40, h 104)</code></p>
  
  <p>I would expect both to be the <code>intrinsicSize</code> but it seems <code>systemLayoutSizeFittingSize:</code> ignores the <code>preferredMaxLayoutWidth</code></p>
  
  <p>Is somebody able to explain it to me?</p>
  
  <p>Edit: 
  Also</p>
  
  <pre><code>label.setNeedsLayout()
  label.layoutIfNeeded() 
  
  let layoutSize = label.systemLayoutSizeFittingSize(UILayoutFittingCompressedSize)
  
  let intrinsicSize = label.intrinsicContentSize()
  </code></pre>
  
  <p>doesn't change the results</p>