registerHeadlessDispatcher method

@override Future registerHeadlessDispatcher(Function dispatcher)

Registering callback raw handle for calling dart callback in background

Implementation

@override
Future registerHeadlessDispatcher(Function dispatcher) async {
  print("$_METHOD_CHANNEL_LOG_TAG registerHeadlessDispatcher: called");

  if (!_bgHandlerInitialized) {
    //Check if the dispatcher raw handle is valid
    final callback = PluginUtilities.getCallbackHandle(dispatcher);
    assert(callback != null,
        "The dispatcher needs to be a static function or a top level function to be accessible as a Flutter entry point.");

    if (callback != null) {
      final CallbackHandle internalChannelCallbackHandle =
      PluginUtilities.getCallbackHandle(_pluginInternalChannel)!;
      await _methodChannel.invokeMethod<void>('registerHeadlessDispatcher', {
        "appCallbackHandle": callback.toRawHandle(),
        "internalChannelHandle": internalChannelCallbackHandle.toRawHandle(),
        "internalEntryPoint": "_pluginInternalChannel"
      });
      _bgHandlerInitialized = true;
    }
  }
}