startDiscovery method

Implementation

@override
Future<Stream<List<BluetoothDevice>>?> startDiscovery({final Duration? duration})async{
  if(!await requestBluetoothPermissions())return null;
  methodChannel.invokeMethod("startDiscovery");
  if( duration != null && ! await isAllServicesDisposed() ) {
    Future.delayed(duration).then((_)async{
      if( await isAllServicesDisposed())return;
      cancelDiscovery();
    });
  }
  if(_stream != null ) {
    return _stream!.stream;
  }
  _stream = StreamController();

  try {
devicesEventChannel.receiveBroadcastStream().listen((data){
    if(data is! List)return;
    lastSeenDevices.clear();
    for(final dynamic data in data){
      try {
        final BluetoothDevice device = BluetoothDevice.fromParsed(data);
        lastSeenDevices.add(device);
      }catch(_){}

      continue;
    }
    _stream!.sink.add(lastSeenDevices);

  });
  return _stream!.stream;
  }
  catch(e){
    return null;
  }

}