title: Cast from 'MDLMaterialProperty?!'?
body: <p>I'm working with the parse framework for an App that I'm converting to Xcode 7.  One of the interesting errors which has occurred as part of migrating the project is the following: </p>
  
  <blockquote>
    <p>Cast from 'MDLMaterialProperty?!' to unrelated type 'PFUser' always fails</p>
  </blockquote>
  
  <p>The offending line seems to be the "if let" clause below.  I've commented the old line which worked fine in the previous version of Swift for comparison.  </p>
  
  <p>With respect to what this is actually doing - I've passed an array of Parse objects into "likesForThankful" where a pointer "userID" refers to a related PFUser. As part of this method I'm writing individual PFUsers to an array.  </p>
  
  <p>Any help is appreciated - thanks in advance.</p>
  
  <pre><code> //Add PFUsers who Like Post to our FeedItem   
   private func callbackFromLikesProcessing(likesForThankful:[AnyObject], againstFeedItem:FeedItem){
  
      //Instantiate our Objective C compatible array for processing later
      againstFeedItem.parseUsersObjectsWhoLikePost = NSMutableArray()
  
      //Loop through likes and add PFUsers to array of users who like post
      for usersWhoLikePost in likesForThankful{
          // if let parseUserWhoLikesPost = usersWhoLikePost["userID"] as PFUser{
          if let parseUserWhoLikesPost = usersWhoLikePost["userID"] as? PFUser {
              againstFeedItem.parseUsersObjectsWhoLikePost.addObject(parseUserWhoLikesPost)
          }
      } 
  </code></pre>
  
  <p>Andrew</p>