title: Difference between leftAnchor and leadingAnchor?
body: <p>I have been working with constraints in Swift for iOS, and most of the naming conventions/documentation make things quite self explanatory, but one thing that has recently confused me is two pairs of the NSLayoutXAxisAnchor class:</p>
  
  <pre><code>leadingAnchor, leftAnchor
  </code></pre>
  
  <p>along with</p>
  
  <pre><code>trailingAnchor, rightAnchor
  </code></pre>
  
  <p>When I have set constraints programmatically in my iOS app, I have found that I can use these totally interchangeably. If I use leadingAnchor, run the app and observe the behavior, and then use leftAnchor, run the app and observe the behavior, it functions exactly the same.</p>
  
  <p>I checked out the documentation from developer.apple.com, and the results are even exactly the same (ignoring the difference in names). For example comparing the leadingAnchor and leftAnchor:</p>
  
  <blockquote>
    <p>"Use this anchor to create constraints with the view’s leading edge.
    You can only combine this anchor with a subset of the
    NSLayoutXAxisAnchor anchors. You can combine a leadingAnchor with
    another leadingAnchor, a trailingAnchor, or a centerXAnchor. For more
    information, see NSLayoutAnchor Class Reference."</p>
  </blockquote>
  
  <p>compare to:</p>
  
  <blockquote>
    <p>"Use this anchor to create constraints with the view’s left edge. You
    can only combine this anchor with a subset of the NSLayoutXAxisAnchor
    anchors. You can combine a leftAnchor with another leftAnchor, a
    rightAnchor, or a centerXAnchor. For more information, see
    NSLayoutAnchor Class Reference."</p>
  </blockquote>
  
  <p>Does anyone know if there is any intended difference between these properties?</p>