State restoration in MSMessagesAppViewController

I would like to have this state restoration but when I assigned the `restorationIdentifier` and conforms to UIViewControllerRestoration protocol, the method below

does not even get called. Any ideas?

Is the state restoration not enabled in the App Extension?

extension MessagesViewController: UIViewControllerRestoration {
  class func viewControllerWithRestorationIdentifierPath(identifierComponents: [AnyObject], coder: NSCoder) -> UIViewController? {
    print("IDENTIFIER COMPONENTS: \(identifierComponents)")
    return nil
  }
}

Cheers