static func createLoginDialog(buttonPressed: @escaping (_ username:String, _ pw:String) -> Void) -> UIAlertController {
        let alert = UIAlertController(title: "Login", message: "", preferredStyle: .alert)

        let loginAction = UIAlertAction(title: "Log in", style: .default, handler: { _ in
            let u = alert.textFields![0].text!
            let p = alert.textFields![1].text!
            buttonPressed(u,p)
        })

        alert.addAction(loginAction)
        loginAction.isEnabled = false

        var textFields: [UITextField] = []

        alert.addTextField { textField in
            textField.placeholder = "Enter Username"
            textFields.append(textField)
            NotificationCenter.default.addObserver(forName: UITextField.textDidChangeNotification,
                                                   object: textField,
                                                   queue: .main) { _ in
                if textFieldsAreValid(textFields) {
                    loginAction.isEnabled = true
                }
            }
        }

        alert.addTextField { textField in
            textField.placeholder = "Enter Password"
            textFields.append(textField)
            NotificationCenter.default.addObserver(forName: UITextField.textDidChangeNotification,
                                                   object: textField,
                                                   queue: .main) { _ in
                if textFieldsAreValid(textFields) {
                    loginAction.isEnabled = true
                }
            }
        }

        func textFieldsAreValid(_ textFields: [UITextField]) -> Bool {
            textFields.allSatisfy { !($0.text ?? "").isEmpty } //Do the needed tests, I just check if not empty
        }

        return alert
    }