HarmonyOS $$双向绑定问题

@Entry  
@Component  
struct ToggleExample {  
  @State ison: boolean = false  
  build() {  
    Column({ space: 10 }) {  
      Text('type: Switch').fontSize(12).fontColor(0xcccccc).width('90%')  
      Flex({ justifyContent: FlexAlign.SpaceEvenly, alignItems: ItemAlign.Center }) {  
        Text(JSON.stringify(this.ison))  
        Toggle({ type: ToggleType.Switch, isOn: $$this.ison })  
          .selectedColor('#007DFF')  
          .switchPointColor('#FFFFFF')  
          .onChange((isOn: boolean) => {  
            console.info('Component status:' + isOn)  
          })  
      }.width('100%').padding(24)  
    }  
  }  
}