Ios UITabBar生命周期'；的方法不会从后台启动

我有一个

uitabar

控制器作为主控制器，有两个选项卡。每个选项卡都是一个

NavigatorViewController

，其中嵌入了

UIViewController

如果在上一次冷启动后从后台打开应用程序，则不会出现

视图

（

UITabBarController

，

UIViewController

）

---

当用户来自后台时，我如何调用uitabarchildren的生命周期？（即：来自通知）

当应用程序来自后台时，对于任何活动的vc调用非

viewWillDisplay/viewDidDisplay

，您需要收听应用程序委托，如

applicationWillEnterForegroundNotification

NotificationCenter.default.addObserver(self, selector: #selector(applicationWillEnterForegroundNotification), name: UIApplication.willEnterForegroundNotification, object: nil)

class VC: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Listen for application event somewhere early like `ViewDidLoad`
        NotificationCenter.default.addObserver(self, selector: #selector(applicationWillEnterForegroundNotification), name: UIApplication.willEnterForegroundNotification, object: nil)
    }

    // Implement a function that you want to execute when event happen
    @objc func applicationWillEnterForegroundNotification() {
        // Do anything before application Enter Foreground
    }

    // Remove observer when the controller is going to remove to prevent further issues
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
}

---

---

这不在生命周期中，因为在后台模式或其他应用程序事件期间，控制器的状态没有改变

您应该遵守

applicationWillEnterForegroundNotification

NotificationCenter.default.addObserver(self, selector: #selector(applicationWillEnterForegroundNotification), name: UIApplication.willEnterForegroundNotification, object: nil)

class VC: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        // Listen for application event somewhere early like `ViewDidLoad`
        NotificationCenter.default.addObserver(self, selector: #selector(applicationWillEnterForegroundNotification), name: UIApplication.willEnterForegroundNotification, object: nil)
    }

    // Implement a function that you want to execute when event happen
    @objc func applicationWillEnterForegroundNotification() {
        // Do anything before application Enter Foreground
    }

    // Remove observer when the controller is going to remove to prevent further issues
    deinit {
        NotificationCenter.default.removeObserver(self)
    }
}

---

您可以在

控制器中向
UIApplicationWillEnterForeground添加一个
观察者

在某个应用程序离开后台状态前往
成为活跃的应用程序

当您导航到其他屏幕时，不要忘记删除观察器。