避免在iOS Swift中创建多个ViewController实例 [英] Avoid creation of multiple ViewController instances, iOS Swift

问题描述

在AppDelegate中，无论何时收到VoIP呼叫(推送通知)，都会调用以下函数，从而创建"VideoCallViewController"的多个实例

In AppDelegate, the below function gets called whenever VoIP call (push notification) is received thereby creating multiple instances of "VideoCallViewController"

我使用了deinit(在VideoCallViewController中)，如下所示，检查在创建"VideoCallViewController"的新实例之前是否先取消对"VideoCallViewController"的先前实例的使用，令我惊讶的是print("Deinitializing VC)' t被调用，将实例保留在内存中.

I've used deinit (in VideoCallViewController) as shown below, to check if the previous instance of "VideoCallViewController" was being de-initialised before a new instance of "VideoCallViewController" is created, to my surprise print("Deinitializing VC) wasn't called, leaving the instance in memory.

如果AppDelegate中已经存在VideoCallViewController的实例，如何显示VideoCallViewController及其导航控制器.

How can I show VideoCallViewController with its Navigation Controller if an instance of VideoCallViewController already exists from AppDelegate.

在VideoCallViewController中

deinit {
  print("Deinitializing VC)
}

在AppDelegate中

func pushRegistry(_ registry: PKPushRegistry, didReceiveIncomingPushWith payload: PKPushPayload, forType type: PKPushType) {

    let storyboard = UIStoryboard(name: "Main", bundle: nil)
    videoVC = storyboard.instantiateViewController(withIdentifier: "VideoCallViewController") as! VideoCallViewController

    self.window = UIWindow(frame: UIScreen.main.bounds)
    self.window?.rootViewController = videoVC
    self.window?.makeKeyAndVisible()

}

推荐答案

可能的解决方案:创建对可为空窗口的单例保存引用，负责视频通话流程.在通知上更改可见窗口.在通话结束时-返回到应用程序主窗口.

Possible solution: Create singleton holding reference to nullable window, responsible for video calls flow. On notification change visible windows. On call end - return to the application main window.

E.G. :

class VideoCallManager {
    //MARK: - Singleton
    static let sharedInstance = VideoCallManager()
    private init() {}

    private var videoCallWindow: UIWindow?

    func navigateToVideoCallViewController() {
        if let window = self.videoCallWindow, window.keyWindow {
             //VideoCallViewController is displayed at the moment.
             return
        }

        videoCallWindow = UIWindow.init(frame: UIScreen.mainScreen().bounds)
        let storyboard = UIStoryboard(name: "Main", bundle: nil)
        videoVC = storyboard.instantiateViewController(withIdentifier: "VideoCallViewController") as! VideoCallViewController

        self.videoCallWindow?.rootViewController = videoVC
        self.videoCallWindow?.makeKeyAndVisible()
    }

    func returnToWindowOfAppDelegate() {
        if let window = self.videoCallWindow, window.keyWindow {
            (UIApplication.sharedApplication().delegate as? AppDelegate)?.window?.makeKeyAndVisible()

            self.videoCallWindow = nil
        }
    }
}

您的方法如下:

func pushRegistry(_ registry: PKPushRegistry, didReceiveIncomingPushWith payload: PKPushPayload, forType type: PKPushType) {
    VideoCallManager.sharedInstance.navigateToVideoCallViewController()
}

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