UserSearchViewController.swift

var userRef: DatabaseReference!
var resultsArray = [[String:String]]()


var handle: AuthStateDidChangeListenerHandle?
var currentUser: User?


override func viewDidLoad() {
   super.viewDidLoad()


   // Do any additional setup after loading the view.
   userRef = Database.database().reference(withPath: "users")
}


override func viewWillAppear(_ animated: Bool) {
   handle = Auth.auth().addStateDidChangeListener { (auth, user) in
       self.currentUser = user
       if user == nil {
           //Handle logout
       }
   }
}


override func viewWillDisappear(_ animated: Bool) {
   if let handle = handle {
       Auth.auth().removeStateDidChangeListener(handle)
   }
}