override func viewDidLoad() {
        super.viewDidLoad()
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow(_:)), name: NSNotification.Name(rawValue: "keyboardWillShow") , object: NSNotification.Name.UIKeyboardWillShow)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide(_:)), name: NSNotification.Name(rawValue: "keyboardWillHide"), object: NSNotification.Name.UIKeyboardWillHide)
        hideKeyboardWhenTappedAround()
        if let username = defaults.string(forKey: "doc_username") {
            if let password = defaults.string(forKey: "doc_password"){
                login_password.text = password
                login_username.text = username
            }
        }
    }