事件系统eventHub，在组件中使用 eventHub.on 订阅的方法，不能访问组件的变量

 aboutToAppear() { 
   //FIXME TEST 方法会crash 
   FoundationContextHolder.getUIAbilityContext()?.eventHub?.on(AppConst.EVENTHUB_ROCKET, this.componentToTop) 
} 
​ 
 componentToTop() { 
//here crash 
   this.scroller.scrollToIndex(0) 
   Logger.info(AppConst.HOME_TAG, '_scrollTop CTHomePage') 
}

import common from '@ohos.app.ability.common' 
​ 
const eventHub: common.EventHub = (getContext(this) as common.UIAbilityContext).eventHub 
@Entry 
@Component 
struct Index { 
 private scroller: Scroller = new Scroller; 
 private arr: number[] = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9] 
​ 
 // aboutToAppear() { 
 //   eventHub.on('123', ()=>{ 
 //     this.scroller.scrollEdge(Edge.Top) 
 //   }) 
 // } 
​ 
 aboutToAppear() { 
   eventHub.on('123', this.componentToTop.bind(this)) 
} 
​ 
 componentToTop() { 
   //here crash 
   this.scroller.scrollEdge(Edge.Top) 
} 
​ 
 build() { 
   Stack({ alignContent: Alignment.TopStart }) { 
     Scroll(this.scroller) { 
       Column() { 
         ForEach(this.arr, (item: number) => { 
           ListItem() { 
             Text('' + item) 
              .width('100%') 
              .height(100) 
              .fontSize(16) 
              .textAlign(TextAlign.Center) 
              .borderRadius(10) 
              .backgroundColor(0xFFFFFF) 
          } 
        }, (item: string) => item) 
      }.width('100%').backgroundColor(0xDCDCDC) 
    } 
    .scrollBar(BarState.Off) //不显示滚动条 
    .layoutWeight(1) 
​ 
     Button('back top') 
      .onClick(() => { // 点击后回到顶部 
         eventHub.emit('123'); 
      }) 
      .margin({ top: 60, left: 20 }) 
  } 
} 
} 
​