title: How to remove only user-added subviews from my UIView
body: <p>I'm trying to remove all the subviews that I've added to my view, so I've implemented a loop to iterate over the subviews with the following:</p>
  
  <pre><code>for subview in view.subviews {
      println(subview)
      //subview.removeFromSuperview()
  }
  </code></pre>
  
  <p>I tested this by adding a UILabel to my view and then ran this code. The output contained my UILabel but also a _UILayoutGuide. So, my question is how can I determine if a subview is one that I added or one that the system added?</p>