點擊開關按鈕，實現div顯示隱藏

<a-switch ></a-switch>  //開關按鈕
 
html:
<a-switch  @change="onChange"/>  //點擊按鈕  onChange 變成false

<div  v-show="isShow" >123</div>     //隱藏 123
 
methods:
   onChange(checked) {
      console.log(checked);  //checked =false
      this.isShow = checked;     // isShow = false 
    },