How do I receive Strings sent over Bluetooth in Flutter using Flutter Reactive Ble Plugin?

Question

Ok, so I already found out these Uuids of the Bluetooth Device I want to receive Strings from:

 bleNusServiceUUID  = '6e400001-b5a3-f393-e0a9-e50e24dcca9e';
 bleNusCharRXUUID   = '6e400002-b5a3-f393-e0a9-e50e24dcca9e';
 bleNusCharTXUUID   = '6e400003-b5a3-f393-e0a9-e50e24dcca9e';

I've already written the boilerplate Code to connect to the Device etc. and that works fine but as soon as I add following code, which should (theoretically) just read the characteristic, nothing works anymore and my device gets disconnected.

(this Function gets called as soon as the (right) device is connected):

Future<void> foo(String id) async {

  FlutterReactiveBle flutterReactiveBle = FlutterReactiveBle();

  flutterReactiveBle.connectToDevice(
    id: id,
    servicesWithCharacteristicsToDiscover: {Uuid.parse('6e400001-b5a3-f393-e0a9-e50e24dcca9e'): [Uuid.parse('6e400002-b5a3-f393-e0a9-e50e24dcca9e'), Uuid.parse('6e400003-b5a3-f393-e0a9-e50e24dcca9e')]},
    connectionTimeout: const Duration(seconds: 2),
  ).listen((connectionState) async {

    final characteristic = QualifiedCharacteristic(
        serviceId: Uuid.parse('6e400001-b5a3-f393-e0a9-e50e24dcca9e'),
        characteristicId: Uuid.parse('6e400002-b5a3-f393-e0a9-e50e24dcca9e'),
        deviceId: id);
    final response = await flutterReactiveBle.readCharacteristic(characteristic);

    if (response != null) {
      print(response.toString());
    }
  }, onError: (Object error) {
    // Handle a possible error
  });
}

Thanks to every answer in advance.

I tried to get the String sent by a bluetooth device but didn't get anything but errors.

Answer 1

Ok I fixed it myself, here my Resolution for anyone who might have this problem in the future:

(Call this after the device is connected succesfully):

Future<void> _startNotifications() async {
  print("start getting Data");
  await flutterReactiveBle.subscribeToCharacteristic(characteristic).listen((data) {
    print(data);
    //Further Data Handling
  },
  onError: (dynamic error) {
    print('Error subscribing to Char.');
    print('Error: ' + error.toString());
  },
  onDone: () {
    print('Seemingly Done (Whatever that means.)');
  }
  );
}