ios - 获取谷歌地图的经纬度中心

Question

我想显示全屏 mapView，始终获取 mapView 中心的纬度和经度并在该点显示标记。

func mapView(_ mapView: GMSMapView, didChange position: GMSCameraPosition) {

    let lat = mapView.camera.target.latitude
    print(lat)

    let lon = mapView.camera.target.longitude
    print(lon)


    marker.position = CLLocationCoordinate2DMake(CLLocationDegrees(centerPoint.x) , CLLocationDegrees(centerPoint.y))
    marker.map = self.mapView
    returnPostionOfMapView(mapView: mapView)

  }

  func mapView(_ mapView: GMSMapView, idleAt position: GMSCameraPosition) {
    print("idleAt")

    //called when the map is idle

    returnPostionOfMapView(mapView: mapView)

  }

  func returnPostionOfMapView(mapView:GMSMapView){
    let geocoder = GMSGeocoder()
    let latitute = mapView.camera.target.latitude
    let longitude = mapView.camera.target.longitude




    let position = CLLocationCoordinate2DMake(latitute, longitude)
    geocoder.reverseGeocodeCoordinate(position) { response , error in
      if error != nil {
        print("GMSReverseGeocode Error: \(String(describing: error?.localizedDescription))")
      }else {
        let result = response?.results()?.first
        let address = result?.lines?.reduce("") { $0 == "" ? $1 : $0 + ", " + $1 }

        print(address)
//        self.searchBar.text = address
      }
    }
  }

我使用此代码如何知道 returnPostionOfMapView 方法中返回的纬度和经度是中心 mapView 的位置并在此位置显示标记？

Answer 1

通过使用 google map 的 func mapView(_ mapView: GMSMapView, didChange position: GMSCameraPosition) 委托(delegate)，您正确地获得了 map 的中心。

取中心坐标变量

var centerMapCoordinate:CLLocationCoordinate2D!

实现此委托(delegate)以了解中心位置。

func mapView(_ mapView: GMSMapView, didChange position: GMSCameraPosition) {
    let latitude = mapView.camera.target.latitude
    let longitude = mapView.camera.target.longitude
    centerMapCoordinate = CLLocationCoordinate2D(latitude: latitude, longitude: longitude)
    self.placeMarkerOnCenter(centerMapCoordinate:centerMapCoordinate)
}

在中心点放置标记的功能

func placeMarkerOnCenter(centerMapCoordinate:CLLocationCoordinate2D) {
    let marker = GMSMarker()
    marker.position = centerMapCoordinate
    marker.map = self.mapView
}

在这种情况下你会得到很多标记。所以保持全局持有marker并检查它是否已经存在，只需更改位置

var marker:GMSMarker!

func placeMarkerOnCenter(centerMapCoordinate:CLLocationCoordinate2D) {
    if marker == nil {
        marker = GMSMarker()
    }
    marker.position = centerMapCoordinate
    marker.map = self.mapView
}