使用 Xamarin.Forms.Maps 上 Xamarin.Forms21920411ZCBD85089

Question

I'm having a weird problem on iOS only , I'm using Xamarin.Forms.Maps ( copy paste from docs ), my iOS simulator has its Mock location to "Apple" and I'm using Xamarin.Essentials Geolocation to get the设备位置：

private async Task ExecuteDisplayCurrentLocationCommand()
    {
        IsBusy = true;

        try
        {
            MainThread.BeginInvokeOnMainThread(async () =>
            {
                var request = new GeolocationRequest(GeolocationAccuracy.High, TimeSpan.FromSeconds(10));
                var cts = new CancellationTokenSource();
                var location = await Geolocation.GetLocationAsync(request, cts.Token);

                if (location != null)
                {
                    if (location.IsFromMockProvider)
                    {
                        //await App.Current.MainPage.DisplayAlert("Wrong Location", "Your device is giving a false location, please turn on location services in the settings", "Cancel");
                        Position position1 = new Position(location.Latitude, location.Longitude);
                        MapSpan mapSpan1 = MapSpan.FromCenterAndRadius(position1, Distance.FromKilometers(8));
                        Map.MoveToRegion(mapSpan1);
                    }
                    Position position = new Position(location.Latitude, location.Longitude);
                    MapSpan mapSpan = MapSpan.FromCenterAndRadius(position, Distance.FromKilometers(8));
                    Map.MoveToRegion(mapSpan);
                }
                //else
                //{
                //    await App.Current.MainPage.DisplayAlert("Can't get location", "", "Cancel");
                //}
            });
        }
        catch (FeatureNotSupportedException)
        {
            await App.Current.MainPage.DisplayAlert("Location feature not supported", "Your device doesn't support location, please use a newer device", "Ok");
        }
        catch (FeatureNotEnabledException)
        {
            //await App.Current.MainPage.DisplayAlert("Location isn't enabled", "Your device doesn't have location services enabed, please turn on location services in the settings", "Ok");
        }
        catch (PermissionException)
        {
            await App.Current.MainPage.DisplayAlert("Location permission", "Your device isn't giving us permission to use your location, please turn on location services in the settings", "Ok");
        }
        catch (Exception ex)
        {
            Debug.WriteLine(ex);
        }
        finally
        {
            IsBusy = false;
        }
    }

我正在使用MainThread.BeginInvokeOnMainThread因为它需要 iOS 才能工作

奇怪的是，当我运行代码并到达Map.MoveToRegion(mapSpan); 在if (location.IsFromMockProvider)方法中，它转到CustomMapRenderer的GetViewForAnnotation并运行var customPin = GetCustomPin(annotation as MKPointAnnotation); 方法好像它试图获取 map 引脚，这对我来说没有意义，这会引发System.Reflection.TargetInvocationException因为CustomPin GetCustomPin(MKPointAnnotation annotation)的annotation参数是 null，当然它不应该调用对的？

奇怪的是对方法的调用： var customPin = GetCustomPin2(annotation as MKPointAnnotation); 实际上将 lat 和 lon 作为参数传递，我很困惑。

它应该首先调用它吗？

有谁知道它为什么这样做？ 我在 Android 上没有遇到这个问题，目前无法检查它是否在 Android 上也有同样的问题，但如果有人知道它为什么会这样以及解决方案是什么，请帮忙。

谢谢

Answer 1

如果您删除插件Xamarin.Essentials Geolocation问题是否仍然存在？

你在真机上试过吗？

---

查看定义（从文档复制）

当注释的位置在 map 上可见时调用 GetViewForAnnotation 方法，用于在显示之前自定义注释。

如果您没有在 map 上设置Pins ，则不应调用此方法。

尝试添加以下代码

if(annotation == null)  return null;  //add this line
var customPin = GetCustomPin(annotation as MKPointAnnotation);