React Native iOS Native View send event with proper reactTag

I have a iOS Native View which is a UIView with a map view and a UIView. The map has a event called 'regionDidChangeAnimated', I want to send event to the React Native. But the reactTag is not right.

- (UIView *)view
{
  CGRect screenRect = [[UIScreen mainScreen] bounds];

  UIView *frameView = [[UIView alloc] initWithFrame:screenRect];

  CGRect frameRect = frameView.bounds;

  MAMapView *mapView;
  mapView = [[MAMapView alloc] initWithFrame:frameRect];
  self.mapview = mapView;
  mapView.delegate = self;

  [frameView addSubview:mapView];

  RCTFixedPin* pin = [[RCTFixedPin alloc] initWithFrame:CGRectMake(0, 0, screenRect.size.width, 260)];
  pin.userInteractionEnabled = NO;
  [frameView addSubview:pin];

  return frameView;
}

- (void)mapView:(MAMapView *)mapView regionDidChangeAnimated:(BOOL)animated {

  if (self.dragging) {
    self.dragging = NO;
  }


  MACoordinateRegion region = mapView.region;
  NSDictionary *event = @{
                          ***@"target": ,***
                          @"region": @{
                              @"latitude": @(region.center.latitude),
                              @"longitude": @(region.center.longitude),
                              @"latitudeDelta": @(region.span.latitudeDelta),
                              @"longitudeDelta": @(region.span.longitudeDelta),
                              }
                          };
  [self.bridge.eventDispatcher sendInputEventWithName:@"topChange" body:event];
}