How Do I Set Up Push Notifications in the iOS SDK (v2, Legacy)?

// Inherit protocols
class AppDelegate: UIResponder, UIApplicationDelegate, UNUserNotificationCenterDelegate, MessagingDelegate {
    var gameballApp: Gameball?
    // ...
}

FirebaseApp.configure()
registerForPushNotifications()

func registerForPushNotifications() {
    UNUserNotificationCenter.current()
        .requestAuthorization(options: [.alert, .sound, .badge]) {
            [weak self] granted, error in
            UNUserNotificationCenter.current().delegate = self
            Messaging.messaging().delegate = self
            guard granted else { return }
            self?.getNotificationSettings()
    }
}

func getNotificationSettings() {
    UNUserNotificationCenter.current().getNotificationSettings { settings in
        guard settings.authorizationStatus == .authorized else { return }
        DispatchQueue.main.async {
            UIApplication.shared.registerForRemoteNotifications()
        }
    }
}