Swift - How to open specific view controller when push notification received?

Swift 5

Simply, implement the following function which will be called when the user clicked on the notification.

In AppDelegate:

// This method is called when user clicked on the notification
func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void)
{
    // Do whatever you want when the user tapped on a notification
    // If you are waiting for specific data from the notification 
    // (e.g., key: "target" and associated with "value"), 
    // you can capture it as follows then do the navigation:

    // You may print `userInfo` dictionary, to see all data received with the notification.
    let userInfo = response.notification.request.content.userInfo
    if let targetValue = userInfo["target"] as? String, targetValue == "value"
    {
        coordinateToSomeVC()
    }
    
    completionHandler()
}

private func coordinateToSomeVC()
{
    guard let window = UIApplication.shared.keyWindow else { return }

    let storyboard = UIStoryboard(name: "YourStoryboard", bundle: nil) 
    let yourVC = storyboard.instantiateViewController(identifier: "yourVCIdentifier")
    
    let navController = UINavigationController(rootViewController: yourVC)
    navController.modalPresentationStyle = .fullScreen

    // you can assign your vc directly or push it in navigation stack as follows:
    window.rootViewController = navController
    window.makeKeyAndVisible()
}

Note:

If you navigate to a specific controller based on the notification, you should care about how you will navigate back from this controller because there are no controllers in your stack right now. You must instantiate the controller you will back to. In my case, when the user clicked back, I instantiate the home controller and make it the app root again as the app will normally start.

When you app is in closed state you should check for launch option in

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

and call your API.

Example:

if let option = launchOptions {
  let info = option[UIApplicationLaunchOptionsKey.remoteNotification]
  if (info != nil) {
    goAnotherVC()
  }
}