Includes PubNub push notification configuration & message listener too.

PubNub_PushNotifications_And_PubSubListener

import UIKit
import PubNub

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var pubnub: PubNub!
    let listener = SubscriptionListener(queue: .main)
    
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        registerForPushNotifications()
        configurePubNub()
        return true
    }

    // MARK: UISceneSession Lifecycle

    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }

    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
        // Called when the user discards a scene session.
        // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
        // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
    }
    
    func registerForPushNotifications() {
        let notification = UNUserNotificationCenter.current()
        notification.delegate = self
        notification.requestAuthorization(options: [.alert, .sound, .badge]) {
            (granted, error) in
            print("Permission granted: \(granted)")
            // 1. Check if permission granted
            guard granted else { return }
            // 2. Attempt registration for remote notifications on the main thread
            DispatchQueue.main.async {
                UIApplication.shared.registerForRemoteNotifications()
            }
        }
    }
    
    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        pubnub.removeAllPushChannelRegistrations(for: deviceToken) { (result) in
            switch result {
            case let .success(response):
              print("all channels removed")
            case let .failure(error):
              print("failed to remove channels")
            }
        }
        pubnub.modifyAPNSDevicesOnChannels(
          byRemoving: [],
          thenAdding: ["151__1__a067448c-736e-4f9a-ac1e"],
          device: deviceToken,
          on: "<Bundle_ID>",        
          environment: .development
         ) { result in
          switch result {
          case let .success(response):
            print("Successful Push Modification Response: \(response)")
          case let .failure(error):
            print("Failed Push List Response: \(error.localizedDescription)")
          }
        }
    }
    
    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable : Any], fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
        print("received remote notification")
    }
    func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
        print("failed to register for remote notification")
    }
}

extension AppDelegate {
    func configurePubNub() {
        let key = "sub-c-bed92252-94e0-11ea-8dc6-429c98eb9bb1"
        
        PubNub.log.levels = [.all]
        PubNub.log.writers = [ConsoleLogWriter(), FileLogWriter()]

        let config = PubNubConfiguration(publishKey: "", subscribeKey: key)
        pubnub = PubNub(configuration: config)
        
        listener.didReceiveMessage = { message in
          print("[Message]: \(message)")
        }
        listener.didReceiveStatus = { status in
          switch status {
          case .success(let connection):
            if connection == .connected {
              print("Status Success: \(connection)")
            }
          case .failure(let error):
            print("Status Error: \(error.localizedDescription)")
          }
        }

        pubnub.add(listener)
        pubnub.subscribe(to: ["151__1__a067448c-736e-4f9a-ac1e"], withPresence: true)
    }
}

extension AppDelegate: UNUserNotificationCenterDelegate {
    func userNotificationCenter(_ center: UNUserNotificationCenter, didReceive response: UNNotificationResponse, withCompletionHandler completionHandler: @escaping () -> Void) {
        print("notification: \(response)")
    }
}