我想你必须做这样的事情：

let tabBar: UITabBarController // get your tab bar
tabBar.selectedIndex = 0 // eg. zero. To be sure that you are on correct tab
if let navigation = tabBar.viewControllers?[tabBar.selectedIndex] as? UINavigationController {
    let storyboard = UIStoryboard.init(name: "Main", bundle: Bundle.main)
    if let chatViewController = storyboard.instantiateViewController(withIdentifier: "chatViewController") as? ChatViewController {
        navigation.pushViewController(chatViewController, animated: true)
    }
 }

好吧，你正在设置当前的window.rootViewController，这应该是我说的TabBarViewController。这就是为什么你不能回到TabBar
你应该做的是

let storyboard = UIStoryboard.init(name: "Main", bundle: nil)
if let chatViewController = storyboard.instantiateViewController(withIdentifier: "chatViewController") as? ChatViewController, let tabBar = storyboard.instantiateViewController(withIdentifier: "tabBar") as? UITabBarController {
    let navigationController = UINavigationController(rootViewController: chatViewController)
    navigationController.viewControllers = [chatViewController]
    tabBar.viewControllers = [navigationController]
    window?.rootViewController = tabBar
}

从选项卡栏控制器中获取当前的导航控制器。您可以使用此功能

func getVisibleViewController(_ rootViewController: UIViewController?) -> UIViewController? {
        
        var rootVC = rootViewController
        if rootVC == nil {
            rootVC = UIApplication.shared.keyWindow?.rootViewController
        }
        
        if rootVC?.presentedViewController == nil {
            return rootVC
        }
        
        if let presented = rootVC?.presentedViewController {
            if presented.isKind(of: UINavigationController.self) {
                let navigationController = presented as! UINavigationController
                return navigationController.viewControllers.last!
            }
            
            if presented.isKind(of: UITabBarController.self) {
                let tabBarController = presented as! UITabBarController
                return tabBarController.selectedViewController!
            }
            
            //UIAlertController
            if presented.isKind(of: UIAlertController.self) {
                let alertController = presented as! UIAlertController
                return alertController.presentingViewController
            }
            return getVisibleViewController(presented)
        }
        return nil
    }

使用该函数，您可以像下面这样导航视图控制器。

let mainStoryboardIpad : UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
                let yourView = mainStoryboardIpad.instantiateViewController(withIdentifier: "yourView") as! NewnoteViewController

                let navi = self.getVisibleViewController(self.window!.rootViewController) as! UINavigationController
               
                navi.pushViewController(yourView, animated: true)

您可以在RootViewController中创建一个方法，在收到推送通知后将用户重定向到特定视图。这是我在上一个项目中所做的。

class RootViewController: UIViewController {
    private var currentView: UIViewController
    
    init() {
        self.currentView = ViewController()
        super.init(nibName: nil, bundle: nil)
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        addChildViewController(currentView)               // 1
        currentView.view.frame = view.bounds              // 2
        view.addSubview(currentView.view)                 // 3
        currentView.didMove(toParentViewController: self) // 4
    }
    
    func showDetailsScreen() {
        if let updateDetailView = UIStoryboard(name: "Main", bundle: nil).instantiateViewController(withIdentifier: "UpdateDetailsNotif") as? UpdateDetailsViewController{
            
            let navController = UINavigationController(rootViewController: updateDetailView)

            addChildViewController(navController)
            navController.view.frame = view.bounds
            view.addSubview(navController.view)
            navController.didMove(toParentViewController: self)
            currentView.willMove(toParentViewController: nil)
            currentView.view.removeFromSuperview()
            currentView.removeFromParentViewController()
            currentView = navController
        }
        
    }
   
}

然后你可以像这样在AppDelegate上调用这个方法：

func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
        let application = UIApplication.shared
  
        AppDelegate.shared.rootViewController.showDetailsScreen()
       
        completionHandler()
    
    }
}

func userNotificationCenter(_ center: UNUserNotificationCenter,
                                didReceive response: UNNotificationResponse,
                                withCompletionHandler completionHandler: @escaping () -> Void) {

        let userInfo = response.notification.request.content.userInfo
        print("didReceive2: ", userInfo)
        Messaging.messaging().appDidReceiveMessage(userInfo)
        
            //        NotificationCenter.default.post(name: NotificationName.openRaceDAyTipsTab, object: nil)
        
        let application = UIApplication.shared
        
        if(application.applicationState == .active) {
            print("user tapped the notification bar when the app is in foreground")
        }
        
        if(application.applicationState == .inactive) {
            print("user tapped the notification bar when the app is in background")
        }
        
        guard let rootViewController = (UIApplication.shared.connectedScenes.first?.delegate as? SceneDelegate)?.window?.rootViewController else {
            return
        }
        print("got active scene")
        
        
            // handle the push notification here
        if let articleId = userInfo["articleId"] as? String {
                // use the articleId in your app logic
                // Create an instance of ArticlesDetailViewController
            let articlesDetailVC = ArticlesDetailViewController.instantiateHome()
            articlesDetailVC.articlesId = articleId
            
            if let tabBarVC = rootViewController as? UITabBarController,
               let navVC = tabBarVC.selectedViewController as? UINavigationController {
                navVC.pushViewController(articlesDetailVC, animated: true)
            }
        }
        
        completionHandler()
    }