title: NSDistributedNotificationCenter not working
body: <p>I'm implementing a VPN app (Packet Tunnel Provider).</p>
  
  <p>I have a "containing" app, and an extension.
   Both app are in sandbox mode.
  I want to use NSDistributedNotificationCenter and send a message from the extension to the containing app, but it's not working.</p>
  
  <p>Here is the code at the extension:</p>
  
  <pre><code>let distributedNotificationCenter = NSDistributedNotificationCenter.defaultCenter()
  distributedNotificationCenter.postNotificationName("myNotification", object: nil, userInfo: nil, deliverImmediately: true)
  </code></pre>
  
  <p>And this is at the containing app:</p>
  
  <pre><code>let distributedNotificationCenter = NSDistributedNotificationCenter.defaultCenter()
  distributedNotificationCenter.addObserver(self, selector: #selector(CNConnectViewController.doNotification(_:)), name: "myNotification", object: nil)
  
  func doNotification(message: NSNotification) {
       NSLog("doNotification")
  }
  </code></pre>
  
  <p>Am I missing something? </p>