https://developers.weixin.qq.com/miniprogram/dev/api/open-api/setting/wx.getSetting.html

通过wx.getSeeting(Object object)获取res.authSetting['scope.userLocationBackground']

同一iphone手机，调用该api结果返回true之后，半分钟之后再获取返回false（中间小程序权限一直是允许后台定位）