title: Cannot invoke findObjectsInBackgroundWithBlock swift error
body: <p>So I ran into this error when getting all the users from parse to my application:</p>
  
  <blockquote>
    <p>Cannot invoke 'findObjectsInBackgroundWithBlock' with an argument list
    of type '(([AnyObject]!, NSError!) -> Void)'</p>
  </blockquote>
  
  <p>trying to run this code: </p>
  
  <pre><code>    var userQuery = PFUser.query()
      userQuery.findObjectsInBackgroundWithBlock({(objects: [AnyObject]!, error: NSError!) -&gt; Void in
  
  
          self.users.removeAll(keepCapacity: true)
  
          for object in objects {
              var user:PFUser = object as PFUser
  
              self.users.append(user.username)
          }
  
          self.tableView.reloadData()
  
  
      })
  </code></pre>
  
  <p>I am using xcode 6.3, is there any solutions? I've tried adding "?" instead of "!"  after [AnyObject] but nothing seems to help.</p>