如何從SceneDelegate中關閉視圖控制器？

我正在開發一個 ios 應用程式（Swift 5），如果應用程式處于脫機狀態，我會嘗試顯示一個螢屏，然后在用戶重新連接時關閉。

我希望 OfflineViewController 在用戶離線時出現，以及用戶在連接時出現的最后一個螢屏。

發生的情況是當我斷開網路連接時出現 OfflineViewController，但是當我連接回網路時它并沒有消失。我嘗試添加一個按鈕來關閉，這也不起作用。

我在下面附上了我的代碼，知道我做錯了什么嗎？

場景委托

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?
    let reachability = try! Reachability()


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        
        guard let _ = (scene as? UIWindowScene) else { return }

        // Send to homepage if logged in, otherwise login screen.
        let accessToken: String? = KeychainWrapper.standard.string(forKey: "accessToken")
        
        // If access token exists, skip login page
        if accessToken != nil {            
            if let windowScene = scene as? UIWindowScene {
                self.window = UIWindow(windowScene: windowScene)
                let mainStoryboard:UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
                let vc = mainStoryboard.instantiateViewController(withIdentifier: "homeTabController") as! TabBarController
                self.window!.rootViewController = vc
            }
        }

        reachability.whenUnreachable = { [self] _ in
            print("Not reachable (Scene delegate)")

            let storyboard = UIStoryboard(name: "Main", bundle: nil)
            
            let vc = storyboard.instantiateViewController(withIdentifier: "OfflineViewController") as! OfflineViewController
            vc.modalPresentationStyle = .fullScreen

            guard let firstScene = UIApplication.shared.connectedScenes.first as? UIWindowScene else {
                return
            }

            guard let firstWindow = firstScene.windows.first else {
                return
            }
            
            let rootVC = firstWindow.rootViewController
            rootVC?.dismiss(animated: true, completion: nil)
            rootVC!.present(vc, animated: true, completion: nil)

        }

        do {
            try reachability.startNotifier()
        } catch {
            print("Unable to start notifier")
        }
    }
}

離線視圖控制器

import UIKit

class OfflineViewController: UIViewController {
    
    let reachability = try! Reachability()

    override func viewDidLoad() {
        super.viewDidLoad()

        do {
            try reachability.startNotifier()
        } catch {
            print("Unable to start notifier")
        }
    }
    
    @IBAction func hitRefresh(_ sender: Any) {
        reachability.whenReachable = { reachability in
                self.dismiss(animated: true, completion: nil)
        }
    }
}

uj5u.com熱心網友回復：

我將開始從OfflineViewController. 解散的邏輯屬于呈現的邏輯。

然后使用whenReachable關閉當前OfflineViewController.

您還應該避免UIApplication.shared.connectedScenes在場景委托代碼中使用。你已經知道那個場景了。沒必要去找。

更新whenUnreachable：

    reachability.whenUnreachable = { [self] _ in
        print("Not reachable (Scene delegate)")

        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        
        let vc = storyboard.instantiateViewController(withIdentifier: "OfflineViewController") as! OfflineViewController
        vc.modalPresentationStyle = .fullScreen

        guard let winScene = (scene as? UIWindowScene) else { return }

        guard let firstWindow = winScene.windows.first else {
            return
        }
        
        let rootVC = firstWindow.rootViewController
        rootVC?.dismiss(animated: true, completion: nil)
        rootVC?.present(vc, animated: true, completion: nil)
    }

添加的whenReachable：

    reachability.whenReachable = { [self] _ in
        print("Reachable (Scene delegate)")

        guard let winScene = (scene as? UIWindowScene) else { return }

        guard let firstWindow = winScene.windows.first else {
            return
        }
        
        let rootVC = firstWindow.rootViewController
        rootVC?.dismiss(animated: true, completion: nil)
    }

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