如何覆盖UIViewController中的"view"属性？

import UIKit

class CustomView: UIView {
    // 在这里添加自定义属性和方法
}

import UIKit

class CustomViewController: UIViewController {
    override func loadView() {
        view = CustomView()
    }
}

import UIKit

class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        let customViewController = CustomViewController()
        let navigationController = UINavigationController(rootViewController: customViewController)

        window = UIWindow(frame: UIScreen.main.bounds)
        window?.rootViewController = navigationController
        window?.makeKeyAndVisible()

        return true
    }
}