One pattern for getting rid of optionals in a xib-loaded UIViewController

LoginViewController.swift

import UIKit

class LoginViewController: UIViewController {
    private class Controller {
        let usernameField: UITextField
        let passwordField: UITextField

        init(usernameField: UITextField, passwordField: UITextField) {
            self.usernameField = usernameField
            self.passwordField = passwordField
        }

        func attemptLogin() {
            // all nice and non-optional
            let username = usernameField.text
            let password = passwordField.text

            // LoginManager.handleLogin(username: username, password: password)
        }
    }

    private var controller: Controller? = nil

    override func viewDidLoad() {
        super.viewDidLoad()
        guard
            let usernameField = self.usernameField,
            let passwordField = self.passwordField
        else {
            fatalError("View not initialized properly")
        }

        self.controller = Controller(
            usernameField: usernameField,
            passwordField: passwordField
        )
    }

    @IBOutlet var usernameField: UITextField!
    @IBOutlet var passwordField: UITextField!

    @IBAction func login(_ sender: Any) {
        controller?.attemptLogin()
    }
}