为什么在执行通知onclick时选项卡栏隐藏

Question

let db = Firestore.firestore()
                db.collection("Orders").document(Flag1!).getDocument() { (docSnapshot, err) in

                    if let err=err {
                        print("Error getting documents: \(err)")
                    } else {
                        guard let docSnapshot = docSnapshot, (docSnapshot.exists) else { return }
                        let myData = docSnapshot.data()
                        let status:String = myData!["Status"] as? String ?? ""
                        if status == "OrderModified"{
                            var topWindow: UIWindow? = UIWindow(frame: UIScreen.main.bounds)
                            topWindow?.rootViewController = UIViewController()
                            topWindow?.windowLevel = UIWindow.Level.alert + 1
                            let alert: UIAlertController =  UIAlertController(title: "Message", message: "this order was modified", preferredStyle: .alert)
                            alert.addAction(UIAlertAction.init(title: "OK", style: .default, handler: { (alertAction) in
                                topWindow?.isHidden = true
                                topWindow = nil
                            }))
                            topWindow?.makeKeyAndVisible()
                            topWindow?.rootViewController?.present(alert, animated: true, completion:nil)
                        }else{
                            let storyBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
                            let presentViewController =   storyBoard.instantiateViewController(withIdentifier: "AltWhenNoPs") as! AltWhenNoPs
                            presentViewController.orderid = Flag1!
                            let navigationController = UINavigationController(rootViewController: presentViewController)
                            self.window?.rootViewController = navigationController
                        }
                    }
                }

我在appdelegate中编写了代码，用于在单击通知时导航到特定的视图控制器，上面的代码效果很好，但是问题是当我单击通知时，标签栏不可见。为什么它隐藏了？谁能建议我我在哪里做错了。提前致谢。