微信小程序苹果ios中observer无法监听到属性值，安卓没有问题

properties: {

move_index:{
      type:Number,
      value:-1,
      observer: function (new_val: any, old_val: any)
      {
        console.log("sdfjaslkdfjaslkdfjkl")
        debugger
        console.log(old_val)
        let toViews = ['dayun', "liunian", "liuyue", "liuri", "liushi",]
        // [@ts-ignore](/user/ts-ignore)
        if (toViews[new_val] != this.data.toView )
        {
          // [@ts-ignore](/user/ts-ignore)
          this.setData!({
            toView: toViews[new_val]
          })
        }
      }
    },

}