开启了高精度，拿到坐标还是不准确。

onShow: function () {
    var that = this
    wx.getLocation({
      isHighAccuracy: true,
      type: 'wgs84',
      success(loc){
        console.log(loc)
        that.setData({
          position_lat:loc.latitude,
          position_lng:loc.longitude
        })
      },
      fail(res){
        console.log('fail',res)
      },
      complete(res){
        console.log('comp',res)
      }
    })
  }