Question

我想获得用户的位置，因此我使用James Montemagno's Geolocator Plugin for Xamarin。作者在code-behind.cs文件中使用此代码;我把它提取到一个静态类：

public static class GeoService
{
    public static Position savedPosition;

    public static async Task<Position> GetPosition()
    {
        var lastknown = await ExecuteLastKnownPosition();

        if(lastknown == null)
        {
            var current = await ExecuteGPSPosition();
            if(current != null)
            {
                return current;
            }
            else
            {
                return null;
            }
        }
        return lastknown;
    }

    private static async Task<Position> ExecuteLastKnownPosition()
    {
        try

        {

            var hasPermission = await Utils.CheckPermissions(Permission.Location);

            if (!hasPermission)

                return null;

            var locator = CrossGeolocator.Current;

            locator.DesiredAccuracy = 50;

            //Progress Ring einfügen

            var position = await locator.GetLastKnownLocationAsync();

            if (position == null)
            {
                //Benachrichtigung über null lastknownLocation
                //Aufrufen der CurrentPosition Methode
                return null;
            }

            savedPosition = position;
            return position;
        }

        catch (Exception ex)

        {
            Debug.WriteLine(ex);
            await Application.Current.MainPage.DisplayAlert("Uh oh", "Something went wrong, but don't worry we captured for analysis! Thanks.", "OK");
            return null;
        }

        finally
        {
            //Freigabe der Buttons und Bools
        }


    }

    private static async Task<Position> ExecuteGPSPosition()

    {

        try

        {

            var hasPermission = await Utils.CheckPermissions(Permission.Location);

            if (!hasPermission)

                return null;


            var locator = CrossGeolocator.Current;

            locator.DesiredAccuracy = 100;

            //WarteText/Symbol

            var position = await locator.GetPositionAsync(TimeSpan.FromSeconds(15));

            if (position == null)

            {
                //Warnung, dass kein GPS vorhanden ist
                return null;
            }

            savedPosition = position;
            return position;
        }

        catch (Exception ex)

        {
            await Application.Current.MainPage.DisplayAlert("Uh oh", "Something went wrong, but don't worry we captured for analysis! Thanks.", "OK");
            return null;
        }

        finally

        {
            //Zurücksetzen von Buttons und Lademodus beenden
        }

    }

    public static async Task<Address> ExecuteTrackingAdress(Position currentPosition)

    {

        try
        {

            //if (savedPosition == null)
            //    return null;

            var hasPermission = await Utils.CheckPermissions(Permission.Location);
            if (!hasPermission)
                return null;

            string mapkey = "Ajbb9XXXXXXatUzUg1w9BSXXXXXVUAEuF4P-TSXJpnvl5OpXXXXXXXXX";
            var locator = CrossGeolocator.Current;

            var addresses = await locator.GetAddressesForPositionAsync(currentPosition, mapkey);
            var address = addresses.FirstOrDefault();
            if (address == null)

            {
                Debug.WriteLine("Keine Adresse vorhanden");
            }

            return address;
        }

        catch (Exception ex)

        {

            await Application.Current.MainPage.DisplayAlert("Uh oh", "Something went wrong, but don't worry we captured for analysis! Thanks.", "OK");
            return null;
        }

        finally

        {

        }

    }
}

现在我有一个ContentPage，当我转到该页面（PushModalAsync）时，视图模型中的构造函数调用GetPosition()方法。有一个权限任务，每当任务运行时，UWP都会提示我提示位置权限。

不幸的是，从这一点来看应用程序正在冻结。我无法选择是/否，并且无法进行互动。

我尝试使用Task.WhenAll()等方法调用方法异步，但每次都会冻结。

这是我在视图模型中编写的最后一个代码

 private async void ExecuteGetPosition()
    {
        IsBusy = true;
        await Task.Yield();
        var positiontask = GeoService.GetPosition();
        var addresstask = GeoService.ExecuteTrackingAdress(positiontask.Result);
        await Task.WhenAll(positiontask, addresstask);
        CurrentPosition = positiontask.Result;
        CurrentAddress = addresstask.Result;
        OnPropertyChanged("CurrentAddressView");
        IsBusy = false;

    }

我假设XAML ContentPage没有正确加载，因此提示窗口会在＆＃34;后面滑动＆＃34; MainWindow或其他什么。

请你能给我一个解决方法来解决这个问题吗？

修改将这些行添加到我的App.xaml.cs OnStart（） - 方法带来了解决方案。 Windows现在正在调用OnStart权限，Android要求获得gps-request权限...疯狂：

var permission = await CrossPermissions.Current.CheckPermissionStatusAsync(Permission.Location);

Answer 1

你在iOS上运行吗？如果是这样，请查看模拟器的控制台日志以查看是否存在隐私错误。我猜它与请求位置权限时要求在info.plist中的隐私声明有关。

查看列出here所列的所有必要隐私声明。

它们包括（查看链接以获取有关何时添加每个的信息）：

<key>NSLocationWhenInUseUsageDescription</key>
<string>This app needs access location when open.</string>

<key>NSLocationAlwaysUsageDescription</key>
<string>This app needs access location when in the background.</string>
<key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
<string>This app needs access location when open and in the background.</string>

冻结许可请求Xamarin.Forms

1 个答案: