如何在 appdelegate 中关闭视图控制器？

Question

我为这样的暂停视图创建了launchScreen。

func applicationWillResignActive(_ application: UIApplication) {
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        let launchScreen = storyboard.instantiateViewController(withIdentifier: "launchScreen")
        launchScreen.restorationIdentifier = "launchScreen"

        var rootViewController = UIApplication.shared.keyWindow?.rootViewController
        while let presentController = rootViewController?.presentedViewController {
            rootViewController = presentController
        }
        rootViewController?.present(launchScreen, animated: false, completion: nil)
    }

func applicationDidEnterBackground(_ application: UIApplication) {

            guard let passcodeManageView = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "passcodeManageView") as? PasscodeManageViewController else { return }
            passcodeManageView.state = State.loginMode
            passcodeManageView.modalPresentationStyle = .overFullScreen

            var rootViewController = UIApplication.shared.keyWindow?.rootViewController
            while let presentController = rootViewController?.presentedViewController {
                rootViewController = presentController
            }
            rootViewController?.present(passcodeManageView, animated: false, completion: nil)

    }

但是，如何在 applicationDidEnterBackground(:_) 中关闭 launchScreen？？

我怎样才能找到特定的视图控制器并解散？？

Answer 1

根据Apple document for applicationDidEnterBackground(_:)`

使用此方法可释放共享资源、使计时器无效并存储足够的应用状态信息以将您的应用恢复到当前状态，以防以后终止。 您还应该禁用对应用用户界面的更新，并避免使用某些类型的共享系统资源（例如用户的联系人数据库）。还必须避免在后台使用 OpenGL ES。

您不应在应用进入后台后关闭启动屏幕。但是如果你仍然想实现它，使用window?.rootViewController? 关闭，因为此时window?.rootViewController? 是启动屏幕

func applicationDidEnterBackground(_ application: UIApplication) {
  if (window?.rootViewController?.isKind(of: YOUR_LAUNCH_SCREEN_CLASS.self))! {
    window?.rootViewController?.dismiss(animated: true, completion: nil)
  }
}