title: How to get NsKeyValueObservationinfo in swift?
body: <p>I want to get <code>observationInfo</code> message, but I just get address when printing <code>observationInfo</code> as per following code:</p>
  
  <pre><code>        let info = self.apple.observationInfo
  
      print("\(info)") //0x0000000100605e50
      debugPrint("\(info.memory)")//"()"
      print("\(info.memory)") //()
  </code></pre>
  
  <p>How to get the whole message of <code>observationInfo</code> ?</p>