convert-device-token-or-fail.swift

   func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        // 1. Convert device token to string
        let tokenParts = deviceToken.map { data -> String in
            return String(format: "%02.2hhx", data)
        }
        let token = tokenParts.joined()
        // 2. Print device token to use for PNs payloads
        print("Device Token: \(token)")
    }

    func application(_ application: UIApplication, didFailToRegisterForRemoteNotificationsWithError error: Error) {
        // 1. Print out error if PNs registration not successful
        print("Failed to register for remote notifications with error: \(error)")
    }