Geolocation.CivicAddress.City 返回空的 win8 Metro 应用程序

Question

我想创建一个简单的应用程序，向我显示当前应用程序所在的城市。 当我尝试粘贴下面的代码时，城市返回空，国家=US返回，但我住在比利时。

据此link 它说： 定位服务提供对定位功能的访问，例如小区三角测量、WiFi（通过 IP 地址）和 GPS。此外，许多现代设备都支持以前面提到的某种方式解析位置，应用程序必须处理位置服务无法解析位置或用户从控制面板禁用位置服务的情况。

我的笔记本电脑没有GPS，但有了IP，它应该知道城市和国家。

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
using Windows.Devices.Geolocation;
using System.Threading.Tasks;

// The Blank Page item template is documented at http://go.microsoft.com/fwlink/?LinkId=234238

namespace AlarmPro
{
    /// <summary>
    /// An empty page that can be used on its own or navigated to within a Frame.
    /// </summary>
    public sealed partial class MainPage : Page
    {


        public MainPage()
        {
            this.InitializeComponent();

            //InitializeLocationServices();
        }

        /// <summary>
        /// Invoked when this page is about to be displayed in a Frame.
        /// </summary>
        /// <param name="e">Event data that describes how this page was reached.  The Parameter
        /// property is typically used to configure the page.</param>
        protected async override void OnNavigatedTo(NavigationEventArgs e)
        {
            TextBlock txt = new TextBlock();
            var location = await InitializeLocationServices();
            txt.Text = location;

            Grid.SetRow(txt, 0);
            Grid.SetColumn(txt, 1);

        }

        private async Task<string> InitializeLocationServices()
        {
            //Initialize geolocator object
            Geolocator geoLocator = new Geolocator();
            try
            {
                //Try resolve the current location
                var position = await geoLocator.GetGeopositionAsync();
                if (position !=null)
                {
                    string city = position.CivicAddress.City;
                    string country = position.CivicAddress.Country;
                    string state = position.CivicAddress.State;
                    string zip = position.CivicAddress.PostalCode;
                    string msg = "I am located in " + country;
                    if (city.Length > 0)
                        msg += ", city of " + city;
                    if (state.Length > 0)
                        msg += ", " + state;
                    if (zip.Length > 0)
                        msg += " near zip code " + zip;
                    return msg;
                }
                return string.Empty;
            }
            catch (Exception)
            {
                //Nothing to do - no GPS signal or some timeout occured.n .
                return string.Empty;
            }
        }
    }
}

Answer 1

可以肯定的是，您需要等待 Geolocator 实际获得位置。

天真的方法是继续尝试在一个while循环中查看是否有新的更新。

您可能希望附加到 PositionChanged 事件处理程序并等待它告诉您有新的更新。

这里有一些直接来自源代码的信息和代码示例。

http://msdn.microsoft.com/en-us/library/windows/apps/br225534.aspx

我确实相信其中还有一些准确性（DesiredAccuracy 属性）设置，也许这​​也有助于使其更加具体。