小编Ace*_*cer的帖子

我收到错误：

类 AppDelegate 没有初始值设定项

并且似乎无法理解为什么。我正在关注本教程。我是初学者，因此非常感谢任何帮助！

我的代码：

import UIKit

@UIApplicationMain

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

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.

        _ = self.window!.rootViewController

        let mainStoryboard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)

        let centerViewController = mainStoryboard.instantiateViewController(withIdentifier: "ViewController") as! ViewController

        let leftViewController = mainStoryboard.instantiateViewController(withIdentifier: "LeftSideViewController") as! LeftSideViewController

        let leftSideNav = UINavigationController(rootViewController: leftViewController)
        let centerNav = UINavigationController(rootViewController: centerViewController)


        centerContainer = MMDrawerController(center: centerNav, …