title: Unique identifier of an UIView object
body: <p>I am having a following problem. </p>
  
  <ol>
  <li>When a certain touch occures on a UIVIew, I want to store this UIView's <strong>unique identifier</strong> (like let's say objectID) so that when I reopen my app again I can check if in the visible UIViews there is the one UIView with the unique ID from the storage. I do not want to store the tag values as object ids because they may not be unique and they are manualy set up. I need to get a unique identifier that is automatically assign by the system. Any ideas hot to get it?</li>
  </ol>