firebase_messaging : no notifications coming through

Question

Explaining the issue :

I've now tried getting firebase_messaging to work for almost a week. I successfully set up an legacy Xcode APNS app, which worked after generating all new certificates, etc. But with firebase_messaging I get no notifications at all. I even gone so far as recreating a new flutter, firebase and appstoreconnect projects/apps. But I got no notifications at all from firebase, either implemented in native Xcode or flutter. If I subscribe to a topic which doesn't exist yet, it's being created; Notifications on Android and Analytics and InAppMessaging on iOS and Android are working fine, so definitely something is working.

What I've tried so far :

• The official example projects for firebase_messaging on native Xcode and Flutter/Dart
• Recreating all licenses/projects
• Sending messages by topic (which I planned to do anyway)
• applying patches/fixes/tips from GitHub/stackoverflow.

Code snippets to recreate the configuration :

Steps to recreate could be just downloading the Firebase Messaging example projects or following the official docs of setting up Firebase Messaging for native Xcode or Flutter. Basic steps to recreate examples listed here :

---

Implemented plugins (all newest versions) :

• firebase_messaging
• firebase_core
• firebase_analytics

Flutter/Dart (main.dart):

void firebaseCloudMessaging_Listeners() {
  if (Platform.isIOS) iOS_Permission();

  firebaseMessaging.getToken().then((token){
    print(token);
  });

  firebaseMessaging.configure(
    onMessage: (Map<String, dynamic> message) async {
      print('on message $message');
    },
    onResume: (Map<String, dynamic> message) async {
      print('on resume $message');
    },
    onLaunch: (Map<String, dynamic> message) async {
      print('on launch $message');
    },
  );
}

void iOS_Permission() {
  firebaseMessaging.requestNotificationPermissions(
      IosNotificationSettings(sound: true, badge: true, alert: true)
  );
  firebaseMessaging.onIosSettingsRegistered
      .listen((IosNotificationSettings settings)
  {
    print("Settings registered: $settings");
  });
}

void subscribeToFB() {
  firebaseMessaging.subscribeToTopic('-------------Sandbox');
  print("--- SUBSCRIBED ---");
}

void unsubscribeFromFB() {
  firebaseMessaging.unsubscribeFromTopic('-------------Sandbox');
  print("--- UNSUBSCRIBED ---");
}

---

Implemented Pods (all newest versions) :

• pod 'Firebase/Messaging'
• pod 'Firebase/Analytics'

Native Xcode (AppDelegate.h):

#import "AppDelegate.h"

@import UserNotifications;

@interface AppDelegate () <UNUserNotificationCenterDelegate>
@end

@implementation AppDelegate

NSString *const kGCMMessageIDKey = @"gcm.message_id";

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  // [START configure_firebase]
  [FIRApp configure];
  // [END configure_firebase]

  // [START set_messaging_delegate]
  [FIRMessaging messaging].delegate = self;
  // [END set_messaging_delegate]

  // Register for remote notifications. This shows a permission dialog on first run, to
  // show the dialog at a more appropriate time move this registration accordingly.
  // [START register_for_notifications]
  if ([UNUserNotificationCenter class] != nil) {
    // iOS 10 or later
    // For iOS 10 display notification (sent via APNS)
    [UNUserNotificationCenter currentNotificationCenter].delegate = self;
    UNAuthorizationOptions authOptions = UNAuthorizationOptionAlert |
        UNAuthorizationOptionSound | UNAuthorizationOptionBadge;
    [[UNUserNotificationCenter currentNotificationCenter]
        requestAuthorizationWithOptions:authOptions
        completionHandler:^(BOOL granted, NSError * _Nullable error) {
          // ...
        }];
  } else {
    // iOS 10 notifications aren't available; fall back to iOS 8-9 notifications.
    UIUserNotificationType allNotificationTypes =
    (UIUserNotificationTypeSound | UIUserNotificationTypeAlert | UIUserNotificationTypeBadge);
    UIUserNotificationSettings *settings =
    [UIUserNotificationSettings settingsForTypes:allNotificationTypes categories:nil];
    [application registerUserNotificationSettings:settings];
  }

  [application registerForRemoteNotifications];
  // [END register_for_notifications]

  return YES;
}

// [START receive_message]
- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[FIRMessaging messaging] appDidReceiveMessage:userInfo];

  // Print message ID.
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
    fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[FIRMessaging messaging] appDidReceiveMessage:userInfo];

  // Print message ID.
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);

  completionHandler(UIBackgroundFetchResultNewData);
}
// [END receive_message]

// [START ios_10_message_handling]
// Receive displayed notifications for iOS 10 devices.
// Handle incoming notification messages while app is in the foreground.
- (void)userNotificationCenter:(UNUserNotificationCenter *)center
       willPresentNotification:(UNNotification *)notification
         withCompletionHandler:(void (^)(UNNotificationPresentationOptions))completionHandler {
  NSDictionary *userInfo = notification.request.content.userInfo;

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[FIRMessaging messaging] appDidReceiveMessage:userInfo];

  // Print message ID.
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);

  // Change this to your preferred presentation option
  completionHandler(UNNotificationPresentationOptionNone);
}

// Handle notification messages after display notification is tapped by the user.
- (void)userNotificationCenter:(UNUserNotificationCenter *)center
didReceiveNotificationResponse:(UNNotificationResponse *)response
         withCompletionHandler:(void(^)(void))completionHandler {
  NSDictionary *userInfo = response.notification.request.content.userInfo;
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);

  completionHandler();
}

// [END ios_10_message_handling]

// [START refresh_token]
- (void)messaging:(FIRMessaging *)messaging didReceiveRegistrationToken:(NSString *)fcmToken {
    NSLog(@"FCM registration token: %@", fcmToken);
    // Notify about received token.
    NSDictionary *dataDict = [NSDictionary dictionaryWithObject:fcmToken forKey:@"token"];
    [[NSNotificationCenter defaultCenter] postNotificationName:
     @"FCMToken" object:nil userInfo:dataDict];
    // TODO: If necessary send token to application server.
    // Note: This callback is fired at each app startup and whenever a new token is generated.
}
// [END refresh_token]

// [START ios_10_data_message]
// Receive data messages on iOS 10+ directly from FCM (bypassing APNs) when the app is in the foreground.
// To enable direct data messages, you can set [Messaging messaging].shouldEstablishDirectChannel to YES.
- (void)messaging:(FIRMessaging *)messaging didReceiveMessage:(FIRMessagingRemoteMessage *)remoteMessage {
  NSLog(@"Received data message: %@", remoteMessage.appData);
}
// [END ios_10_data_message]

- (void)application:(UIApplication *)application didFailToRegisterForRemoteNotificationsWithError:(NSError *)error {
  NSLog(@"Unable to register for remote notifications: %@", error);
}

// This function is added here only for debugging purposes, and can be removed if swizzling is enabled.
// If swizzling is disabled then this function must be implemented so that the APNs device token can be paired to
// the FCM registration token.
- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
  NSLog(@"APNs device token retrieved: %@", deviceToken);

  // With swizzling disabled you must set the APNs device token here.
  // [FIRMessaging messaging].APNSToken = deviceToken;
}
@end

---

The IDEs (Xcode/VS Code @ macOS HS) do not return any errors; also no errors in debug log. The app reports to be working fine but the messages just don't come through.

Can someone please help me with this? Thanks!

Answer 1

The fix was to just remove the suggested .p8 Key File (from Firebase Console > Project Settings > Cloud Messaging) and instead put in the APNS Development and Release Certificates.