HarmonyOS 地图相关问题

import { MapComponent, mapCommon, map } from '@kit.MapKit'; 
import { AsyncCallback } from '@kit.BasicServicesKit'; 
 
@Entry 
@Component 
struct Index { 
  private mapOptions?: mapCommon.MapOptions; 
  private mapController?: map.MapComponentController; 
  private callback?: AsyncCallback<map.MapComponentController>; 
  private marker?: map.Marker; 
 
  aboutToAppear(): void { 
    // 地图初始化参数 
    this.mapOptions = { 
      position: { 
        target: { 
          latitude: 31.984410259206815, 
          longitude: 118.76625379397866 
        }, 
        zoom: 15 
      } 
    }; 
    this.callback = async (err, mapController) => { 
      if (!err) { 
        this.mapController = mapController; 
        // Marker初始化参数 
        let markerOptions: mapCommon.MarkerOptions = { 
          position: { 
            latitude: 31.984410259206815, 
            longitude: 118.76625379397866 
          }, 
          rotation: 0, 
          visible: true, 
          zIndex: 0, 
          alpha: 1, 
          anchorU: 0.5, 
          anchorV: 1, 
          clickable: true, 
          draggable: true, 
          flat: false 
        }; 
        // 创建Marker 
        this.marker = await this.mapController.addMarker(markerOptions); 
      } 
    }; 
  } 
 
  build() { 
    Stack() { 
      Column() { 
        MapComponent({ mapOptions: this.mapOptions, mapCallback: this.callback }); 
        Button("修改marker图片").onClick(() => { 
          this.marker?.setIcon('app_icon.png'); 
        }) 
      }.width('100%') 
    }.height('100%') 
  } 
}