override func viewDidAppear(_ animated: Bool) {

        super.viewDidAppear(true)

        print("*** viewDidAppear ***")

        if FIRAuth.auth()?.currentUser != nil {

            print("CHECK - USER LOGGED IN")

        } else {

            print("CHECK - USER LOGGED OUT")
            self.performSegue(withIdentifier: "segueLogin", sender: nil)
            return

        }
}