Flutter Signalr Listener is not connected in 2nd screen after migrated to null safety stable version - flutter

Question

Chatting was working perfectly before migrating to null safety using signalr. But after migrating It is not working in chatting part.
Scenario is like there are 2 screens where I am using signalr.
1)Chatlist.
2)Chatting with person.
listener in Chatlist is perfect but in 2nd screen it is not working(Just worked when I installed and run for the 1st time). Weird issue.
All was working in old. I am using bloc for statemanagement and also migrated to yield to emit.
Piece of code is like:
void listenOnMessageReceived(
HubConnection hubConnection,
Function(Message? chatMessageReceive) onMessageReceived,
) {
final SocketResponseCallBack chatMessageReceived =
(response) => onMessageReceived(Message.fromJson(response));
final hubMethod = HubMethod(
CHAT_RECEIVED_MESSAGE_METHOD_NAME,
SignalRHelper.toSocketFunction(
CHAT_RECEIVED_MESSAGE_METHOD_NAME, chatMessageReceived));
bool exists = listenOnHubMethod.any((method) => method.methodName == CHAT_RECEIVED_MESSAGE_METHOD_NAME);
if(exists) {
listenOnHubMethod.removeWhere((element) =>
element.methodName == CHAT_RECEIVED_MESSAGE_METHOD_NAME);
SignalRHelper(hubConnection: hubConnection).on(
hubMethod.methodName,
hubMethod.methodFunction,
);
listenOnHubMethod.add(hubMethod);
}else{
SignalRHelper(hubConnection: hubConnection).on(
hubMethod.methodName,
hubMethod.methodFunction,
);
listenOnHubMethod.add(hubMethod);
}
}
I am having 2 types of above code in different screens. but it is working in only 1 screen and not listening in 2nd screen.
here is a piece of signalr listener code:
static MethodInvocationFunc toSocketFunction(
String methodName, SocketResponseCallBack responseCallBack) {
return (arguments) {
try {
if (arguments!.isEmpty) {
throw SocketEmptyResponseException(methodName);
}
final response = arguments.first;
responseCallBack(response);
} on FormatException {
throw SocketResponseException(methodName);
}
};
}
Is there any limitations in migration of stable version or anything else. Every help is appreciable.
Thank you.

Answer 1

Do not use signalR, on IOS it will be impossible to run listener on background or when app is closed and you will miss messages. Use FCM.