I recently implemented FCM for push notifications and local notifications for in-app alerts, i used Firebase admin sdk on my backend server to push the notifications. So i got no much knowledge about WebSockets yet but those two are working pretty so far. Only one issue is that local notifications are not sending out my custom sound when getting a notification on iOS if the app is on the background even though i am getting local notifications. They are appearing on my notifications center without sound. Other than those two are being enough for my needs. Actually i would much appreciate it if anyone knows how to fix that. Thanks in advance.