swift的相关问题

刚开始用swift写程序发现一些奇怪的问题

    var window: UIWindow?

    var navigationController: UINavigationController?

    var rootViewController0: holdViewController?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {

        window = UIWindow(frame:UIScreen().bounds)

        rootViewController0 = holdViewController()

       window?.rootViewController = rootViewController0

        window?.makeKeyAndVisible()

 return true

    }

这样写的话看似没什么问题。但是在holdViewController中的按钮点击事件就会无响应？？？什么鬼

然后控制台会报大量的错误：

[Touch] unexpected nil window in __sendSystemGestureLatentClientUpdate, _windowServerHitTestWindow:; layer =>, touch: phase: Stationary tap count: 1 force: 0.000 window: (null) view: (null) location in window: {0, 0} previous location in window: {0, 0} location in view: {0, 0} previous location in view: {0, 0}

看意思是Window的尺寸有问题啊。

window = UIWindow(frame:UIScreen().bounds)

应该写作

window = UIWindow(frame:UIScreen.main.bounds)

额，好吧。就好气啊，一堆低级错误，复制代码不靠谱啊！！！

第一天，加油！