title: In Swift, for AnyObject, how do I setValue() then call valueForKey()
body: <p>I'd like to store a value in AnyObject then retrieve it later as follows:</p>
  
  <pre><code>var obj:AnyObject = UIButton()
  obj.setValue("James", forKey: "owner")
  obj.valueForKey("owner")
  </code></pre>
  
  <p>However, AnyObject does not allow it even if these methods are available as shown by the error:</p>
  
  <pre><code>setValue:forUndefinedKey:]: this class is not key value coding-compliant for the key owner.'
  </code></pre>
  
  <p>How could this be done?</p>