如何在Swift 4上的didFinishLaunchingWithOptions中获取Notificationcenter数据

Question

我正在开发一个从远程通知中接收数据的应用程序，当通过使用launchOptions轻按Notificationcenter打开应用程序时，我正在尝试使用Notificationcenter将数据从didFinishLaunchingWithOptions传递至ViewController 。 问题是我的viewDidAppear上的观察者没有获取任何数据。

这是我在didFinishLaunchingWithOptions方法上的代码：

func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {


    if let remoteNotification = launchOptions?[.remoteNotification] as?  [AnyHashable : Any] { 

             let nameSchool = remoteNotification["name_school" as! String]
              NotificationCenter.default.post(name: Notification.Name.nameSchool, object: nameSchool)

                }
    }

观察者在viewDidAppear方法中：

    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)


NotificationCenter.default.addObserver(forName: Notification.Name.nameSchool, object: nil, queue: OperationQueue.main) { (nameSchool) in


            let schoolName = nameSchool.object as! String 

            self.messagePopup(message: "Data received")

        }
}

Answer 1

由于您的应用程序（，didFinishLaunchingWithOptions :)将在viewDidAppear之前（根据您的评论）被调用，因此您将必须临时存储从函数中获得的结果，直到您的代码以后可以检索它为止。

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var remoteNotificationAtLaunch: [AnyHashable: Any]?
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        self.remoteNotificationAtLaunch = launchOptions?[.remoteNotification] as?  [AnyHashable : Any]
    }

    ...
}

显然，在收到远程通知时，将您已经拥有的部件保留在AppDelegate中，该部件会在NotificationCenter中生成帖子。 然后在您的视图控制器中，更新viewDidAppear ...

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    observeNotifications()
    checkForNotificationAtLaunch()
}

private func observeNotifications() {
    NotificationCenter.default.addObserver(forName: Notification.Name.nameSchool, object: nil, queue: OperationQueue.main) { (nameSchool) in
        let schoolName = nameSchool.object as! String
        self.processNotification(schoolName: schoolName)
    }
}

private func checkForNotificationAtLaunch() {
    if let appDelegate = UIApplication.shared.delegate as? AppDelegate {
        if let notificationAtLaunch = appDelegate.remoteNotificationAtLaunch,
            let schoolName = notificationAtLaunch["name_school"] as? String {
            processNotification(schoolName: schoolName)
        }
    }
}

private func processNotification(schoolName: String) {
    self.messagePopup(message: "data received")
    // do something with schoolName....
}