在MapView中移动时，无法保存MkLocalSearch结果

Question

当前工作方式是在地图上移动时，它将收集给定mapview区域中的所有条形。但是，有时其中一些搜索结果/注释会消失。

是否可以在搜索后将先前的注释添加到数组，然后在地图上移动后添加所有在该先前数组中不存在的注释，以便所有结果都显示在地图上？

任何建议都将有助于实现此目标。

class BarsAroundMeVC: UIViewController, MKMapViewDelegate, CLLocationManagerDelegate, UIGestureRecognizerDelegate{
    @IBOutlet weak var mapView: MKMapView!

    let locationManager = CLLocationManager()

    override func viewDidLoad()
    {
        super.viewDidLoad()
        locationManager.delegate = self
        locationManager.requestWhenInUseAuthorization()
        locationManager.startUpdatingLocation()

        let mapDragRecognizer = UIPanGestureRecognizer(target: self, action: #selector(didDragMap(gestureRecognizer:)))
        mapDragRecognizer.delegate = self
        self.mapView.addGestureRecognizer(mapDragRecognizer)
    }

    func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool
    {
        return true
    }

    @objc func didDragMap(gestureRecognizer: UIGestureRecognizer)
    {
        if (gestureRecognizer.state == UIGestureRecognizerState.began)
        {
            print("Map drag began")
            self.locationManager.stopUpdatingLocation()
        }

        if (gestureRecognizer.state == UIGestureRecognizerState.ended)
        {
            print("Map drag ended")
            self.locationManager.stopUpdatingLocation()
        }
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation])
    {

        let location = locations[0]
        let center = location.coordinate
        let span = MKCoordinateSpan(latitudeDelta: 0.01, longitudeDelta: 0.01)
        let region = MKCoordinateRegion(center: center, span: span)

        mapView.setRegion(region, animated: true)
        mapView.showsUserLocation = true
        showBarsAroundUser()
    }

    func showBarsAroundUser()
    {
        let request = MKLocalSearchRequest()
        request.naturalLanguageQuery = "bar"
        request.region = mapView.region

        let search = MKLocalSearch(request: request)

        search.start(completionHandler: {(response, error) in
            if(error != nil) 
            {
                print("Error occured in search: \(error!.localizedDescription)")
            }
            else if (response!.mapItems.count == 0)
            {
                print("No matches found")
            }
            else
            {
                for item in response!.mapItems
                {
                    //print("Name = \(item.name)")

                    let annotation = MKPointAnnotation()
                    annotation.coordinate = item.placemark.coordinate
                    annotation.title = item.name
                    self.mapView.addAnnotation(annotation)
                }
            }
        });
    }