实现二次侧滑退出应用

import common from "@ohos.app.ability.common"; 
import { promptAction } from "@kit.ArkUI"; 
 
@Entry 
@Component 
struct IndexComponent { 
  @State textColor: Color = Color.Black; 
 
  onPageShow() { 
    this.textColor = Color.Blue; 
    console.info("IndexComponent onPageShow"); 
  } 
 
  onPageHide() { 
    this.textColor = Color.Transparent; 
    console.info("IndexComponent onPageHide"); 
  } 
 
  firstBcakTimestamp: number = 0; 
 
  onBackPress() { 
    console.info("IndexComponent onBackPress"); 
    this.textColor = Color.Red; 
    let now = Date.now(); 
    if (now - this.firstBcakTimestamp < 1000) { 
      const context = getContext(this) as common.UIAbilityContext 
      context.terminateSelf(); // 终止程序 
    } else { 
      this.firstBcakTimestamp = now; 
      let option: promptAction.ShowToastOptions = { 
        message: "是否继续退出"// 可以是$r图片 
      } 
      promptAction.showToast(option); 
    } 
    return true 
  } 
 
  build() { 
    Column() { 
      Text("Hello World") 
        .fontColor(this.textColor) 
        .fontSize(30) 
        .margin(30) 
    }.width("100%") 
  } 
}