Why are Firebase push notifications only delivered after re-login on fresh iOS installs?

I'm experiencing an issue with Firebase push notifications on iOS devices.

Although Firebase configuration is set correctly and test notifications sent from the Firebase Console are received, notifications initiated from my backend on a freshly installed app are not delivered. After terminating the app, if I log out and then re-login, notifications start working as expected.

Below is my device registration code for the push notification token:

SWIFTCopied
func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
    Messaging.messaging().apnsToken = deviceToken
    deviceTokenString = deviceToken.reduce("", {$0 + String(format: "%02X", $1)})
    fcmTokenString = Messaging.messaging().fcmToken ?? ""

    print("deviceTokenString \(deviceTokenString)")
    print("fcmToken \(Messaging.messaging().fcmToken ?? "")")

    UIViewController().deviceToken = deviceTokenString //This will stored in UserDefault
    UIViewController().fcmToken = fcmTokenString //This will stored in UserDefault
}

Here is a snapshot of the Firebase Console - Messaging configuration:

And the notification received on the device:

The Laravel backend code that triggers the notification is as follows:

PHPCopied
$url = 'https://fcm.googleapis.com/fcm/send';
$FcmToken = User::whereNotNull('fcm_token')->pluck('fcm_token')->all();
// echo "<pre>"; print_r($FcmToken); die;
// $sendusersids = User::whereIn('id', $users_ids)->whereNotNull('fcm_token')->pluck('id')->all();

foreach ($FcmToken as $key => $FcmTokenone) {

    $fcmService = new FCMService();
    // dd($fcmService);

    // $deviceToken = 'eAzUspsvcEvIjjZ0NVuwBp:APA91bHLgRtV-Oa3xl3HbalmZuhbaslU_IO8HnPi15OL8AabK6aSPF-lo7AC1GcA4BL_YW1osBpMXvuc4nXWtOySqjDQDp1tpGcyzwc8QoTd5Ay3_iayoAw';  // Token for the device you want to notify
    // $deviceToken = 'fbb-W4NZQni5DUkk6fgnPy:APA91bGBUCFueEuUZnad-0jKWusKQoygeQtrvGz6BwfSgBv6RLfJh3U-beEXeIp_S36j4xc5NOsFIexSG4xiM4i3iKBGMb3qnbg-NPB6VgjWfuwM6XnAtW8';  // peterson fcm token

    $title = 'GLO Mini Golf Promo code';
    $body = $data['description'];

    $data1 = [
        // "registration_ids" => [$deviceToken],
        // "registration_ids" => [$FcmTokenone[0]],
        "registration_ids" => [$FcmTokenone],
        "notification" => [
            "title" => $title,
            "body" => $body,
        ],
        "data" => [
            "type" => 'group',
            "id" => 123,
        ]
    ];

    $response = $fcmService->sendNotification($data1);
    Log::error("pushnotificaiotn-->".$response);



    $this->client = new Client();
    $this->serverKey = env('FIREBASE_SERVER_KEY'); // Server key from Firebase credentials
    $this->projectId = env('FIREBASE_PROJECT_ID'); // Firebase project ID


    public function sendNotification($notification_data)
    {
        $access_token = self::getAccessToken();

        $device_token = $notification_data['registration_ids'][0];
        $title = $notification_data['notification']['title'];
        $body = $notification_data['notification']['body'];
        $type = $notification_data['data']['type'];
        $id = $notification_data['data']['id'];

        $message = array(
            'token' => $device_token,
            'notification' => [
                "title" => $title,
                "body" => $body,
            ],
            'data' => [
                "type" => (string)$type,
                "id" => (string)$id
            ],
        );

        Log::error("notification_message--->".json_encode($message));

        $arrayToSend = array('message' => $message);

        $curl = curl_init();
        curl_setopt_array($curl, array(
            CURLOPT_URL => "https://fcm.googleapis.com/v1/projects/".$this->projectId."/messages:send",
            CURLOPT_CUSTOMREQUEST => "POST",
            CURLOPT_POSTFIELDS => json_encode($arrayToSend),
            CURLOPT_HTTPHEADER => array(
                "authorization: Bearer " . $access_token,
                "cache-control: no-cache",
                "content-type: application/json"
            ),
        ));
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        $response = curl_exec($curl);
        Log::error("notification_res-->".$response);
        if ($response === false) {
            $error = curl_error($curl);
            Log::error("sendNotification error".$error);
            curl_close($curl);
        }

        curl_close($curl);
        Log::error("sendNotification success ".$response);
        $responseData = json_decode($response, true);
        return true;
    }
}

The notification delivery log shows that a notification was sent successfully, even though it was not received on a fresh install:

[2025-01-23 12:26:40] production.ERROR: pushnotificaiotn-->1
[2025-01-23 12:26:40] production.INFO: Access Token Generated Successfully: {"access_token":"ya29.c...","expires_in":3599,"token_type":"Bearer","created":1737635200}
[2025-01-23 12:26:40] production.ERROR: notification_message--->{"token":"csQwYhf3FUnvuyLVhHCFEq:APA91bFIMKRtNOaRC0p_-Hgl6bgSg7C-lEQ7uBSUHBivNIH5lra8hnl92ZSm9lcfk9N4gpCwwP8w26s3iX0d121ehEr2S7-S7zbSBFgYNUOZaEDDszOUEtL_uHzIgbOykb85Au_zUcED","notification":{"title":"GLO Mini Golf Promo code","body":"test"},"data":{"type":"group","id":"123"}}
[2025-01-23 12:26:41] production.ERROR: notification_res-->{{
"name": "projects/glo-mini-golf-1dac4/messages/1737635200881686"
}}
[2025-01-23 12:26:41] production.ERROR: sendNotification success {{
"name": "projects/glo-mini-golf-1dac4/messages/1737635200881686"
}}

I suspect the issue may be related to how the FCM token is being obtained on fresh installs. Some answers suggest that fetching the token inside didRegisterForRemoteNotificationsWithDeviceToken might be too early, and instead using the Messaging delegate method (didReceiveRegistrationToken) may be more reliable. It also appears that storing the token via a temporary UIViewController instance might lead to issues with token persistence on first install.

Has anyone encountered this issue before, or can point out improvements that ensure the backend always receives a valid FCM token on fresh installs?