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設備位置：

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因為它需要 iOS 才能工作

奇怪的是，當我運行代碼並到達Map.MoveToRegion(mapSpan); 在if (location.IsFromMockProvider)方法中，它轉到CustomMapRenderer的GetViewForAnnotation並運行var customPin = GetCustomPin(annotation as MKPointAnnotation); 方法好像它試圖獲取 map 引腳，這對我來說沒有意義，這會引發System.Reflection.TargetInvocationException因為CustomPin GetCustomPin(MKPointAnnotation annotation)的annotation參數是 null，當然它不應該調用對的？

奇怪的是對方法的調用： var customPin = GetCustomPin2(annotation as MKPointAnnotation); 實際上將 lat 和 lon 作為參數傳遞，我很困惑。

它應該首先調用它嗎？

有誰知道它為什么這樣做？ 我在 Android 上沒有遇到這個問題，目前無法檢查它是否在 Android 上也有同樣的問題，但如果有人知道它為什么會這樣以及解決方案是什么，請幫忙。

謝謝

Answer 1

如果您刪除插件Xamarin.Essentials Geolocation問題是否仍然存在？

你在真機上試過嗎？

---

查看定義（從文檔復制）

當注釋的位置在 map 上可見時調用 GetViewForAnnotation 方法，用於在顯示之前自定義注釋。

如果您沒有在 map 上設置Pins ，則不應調用此方法。

嘗試添加以下代碼

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