[英]Xamarin Android get location with MvvmCross
我想在我的Xamarin Android应用中实现位置服务。 这是代码:
public class LocationService : ILocationService
{
private readonly object _lock = new object();
private static readonly TimeSpan _timeOut = TimeSpan.FromSeconds(20);
private TaskCompletionSource<MvxCoordinates> _taskSource;
private readonly IMvxLocationWatcher _locationWatcher;
private readonly IMvxMainThreadDispatcher _dispatcher;
public Task<MvxCoordinates> GetCurrentLocation()
{
Task<MvxCoordinates> task;
bool startWatcher = false;
lock (_lock)
{
if (_taskSource == null)
{
_taskSource = new TaskCompletionSource<MvxCoordinates>();
startWatcher = true;
}
task = _taskSource.Task;
}
if (startWatcher)
{
StartWatcher();
}
return task;
}
public MvxCoordinates GetLastSeenLocation()
{
var location = _locationWatcher.LastSeenLocation;
if (location == null)
{
return new MvxCoordinates();
}
return new MvxCoordinates()
{
Latitude = location.Coordinates.Latitude,
Longitude = location.Coordinates.Longitude
};
}
public LocationService(IMvxLocationWatcher locationWatcher, IMvxMainThreadDispatcher dispatcher)
{
this._locationWatcher = locationWatcher;
this._dispatcher = dispatcher;
this._locationWatcher.OnPermissionChanged += PermissionChanged;
}
private void StartWatcher()
{
Console.WriteLine("StartWatcher");
_dispatcher.RequestMainThreadAction(() =>
{
if (_locationWatcher.Started)
{
Console.WriteLine("Watcher already started!");
return;
}
_locationWatcher.Start(new MvxLocationOptions() { Accuracy = MvxLocationAccuracy.Coarse },
location =>
{
_locationWatcher.Stop();
OnSuccess(new MvxCoordinates()
{
Latitude = location.Coordinates.Latitude,
Longitude = location.Coordinates.Longitude
});
},
error =>
{
_locationWatcher.Stop();
Console.WriteLine(error.Code);
OnError(new Exception(error.Code.ToString()));
});
Task.Delay(_timeOut).ContinueWith(_ => OnTimeout());
});
}
private void OnTimeout()
{
Console.WriteLine("Timeout");
TaskCompletionSource<MvxCoordinates> source;
lock (_lock)
{
source = _taskSource;
_taskSource = null;
}
source?.SetException(new Exception(MvxLocationErrorCode.Timeout.ToString()));
if (_locationWatcher.Started)
{
_locationWatcher.Stop();
}
}
private void OnSuccess(MvxCoordinates coordinates)
{
Console.WriteLine("Updated: {0}, {1}", coordinates.Longitude.ToString(), coordinates.Latitude.ToString());
TaskCompletionSource<MvxCoordinates> source;
lock (_lock)
{
source = _taskSource;
_taskSource = null;
}
source?.SetResult(coordinates);
}
private void OnError(Exception error)
{
Console.WriteLine("Error: {0}", error.Message);
TaskCompletionSource<MvxCoordinates> source;
lock (_lock)
{
source = _taskSource;
_taskSource = null;
}
source?.SetException(error);
}
private void PermissionChanged(object sender, MvxValueEventArgs<MvxLocationPermission> e)
{
Console.WriteLine("Permission changed: " + e.Value.ToString());
if (e.Value != MvxLocationPermission.Denied)
{
return;
}
TaskCompletionSource<MvxCoordinates> source;
lock (_lock)
{
source = _taskSource;
_taskSource = null;
}
source?.SetException(new Exception(MvxLocationErrorCode.PermissionDenied.ToString()));
}
}
但是我有这个输出:
[0:] mvx:警告:41.12位置服务提供者不可用-返回null 03-05 12:52:08.449 I / mvx(4065):41.12位置服务提供者不可用-返回null ServiceUnavailable 03-05 12:52:08.457 I / mono-stdout(4065):服务不可用
我在模拟器和真实设备上都有这个。 怎么了?
我找到了解决方案。
在Android清单中未检查ACCESS_FINE_LOCATION
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