应用启动时无法从didFinishLaunchingWithOptions访问ViewController

Question

I am having an issue where I am unable to access a function in my viewcontroller.swft file when lunching from a killed app in didFinishLaunchingWithOptions .

I am trying to access the function with viewController?.loadRequestnotificationwaiting(for: url as! String) from AppDelegate which I pass data to the viewcontroller where I can do some stuff. But when I place an alert in the function in the viewcontroller loadRequestnotificationwaiting . The data is not being passed.

Now I use this same method in other areas to pass data to the viewcontroller from the appdelegate and they work fine. It seems to not work when using it in didFinishLaunchingWithOptions

Is the viewcontroller not available yet when trying to access it from didFinishLaunchingWithOptions ?

AppDelegate.swift

class AppDelegate : UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate {
    weak var viewController : ViewController?

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        UNUserNotificationCenter.current().delegate = self
        ConnectionManager.sharedInstance.observeReachability()
        // Override point for customization after application launch.
        FirebaseApp.configure()
        registerForPushNotifications()

        // opened from a push notification when the app is closed
        if let userInfo = launchOptions?[.remoteNotification] as? [String : AnyObject] {
            if let object = userInfo["aps"] {
                let url = object["url"]

                viewController?.loadRequestnotificationwaiting(for: url as! String)
            }
        }
        return true
    }

}

ViewController.swift

class ViewController: UIViewController, WKNavigationDelegate {
    func loadRequestnotificationwaiting(for notification_url_wait : String) {
        notification_url_final_wait = notification_url_wait

        let url = URL(string: notification_url_final_wait!)
        let URLrequest = URLRequest(url: url!)
        self.webView.load(URLrequest)
    }
}

Answer 1

You are relying on your AppDelegate 's viewController property, but you are setting this property in your viewDidLoad method of your view controller; This is fine when a notification is received when your app is already running, since the viewController property is already set.

When a notification causes your application to be launched, the viewController property is not set and the function isn't called.

Assuming that the view controller you need is the initial view controller from your storyboard, you can get the root view controller from your app delegate's window property;

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    UNUserNotificationCenter.current().delegate = self
    ConnectionManager.sharedInstance.observeReachability()
    // Override point for customization after application launch.
    FirebaseApp.configure()
    registerForPushNotifications()

    // opened from a push notification when the app is closed
    if let userInfo = launchOptions?[.remoteNotification] as? [String : AnyObject] {
        if let object = userInfo["aps"],
            let url = object["url"] as? String,
            let viewController = self.window?.rootViewController as? ViewController {
                viewController.loadRequestnotificationwaiting(for: url)
        }
    }
    return true
}

Answer 2

1. if your view controller is root, you can summon it by call UIApplication.shared.keyWindow!.rootViewController! or overwrite it with your viewController
2. you can raise a notification using -[NotificationCenter postNotificationName:object:userInfo:] and observe this notification name in View Controller