我正在尝试使用Xamarin.Forms.Maps实现Xamarin.Forms应用程序，但是我总是陷入异常：
Java.Lang.SecurityException：我的位置需要权限ACCESS_FINE_LOCATION或ACCESS_COARSE_LOCATION
我已经尝试过本教程https://blog.xamarin.com/requesting-runtime-permissions-in-android-marshmallow/中的步骤，但没有得到结果。
有人会有更一致的东西来帮助我吗？
我打算使用非常接近优步的应用程序，如果我无法获得位置权限，我就无法进步。
我的主页在我的PCL中看起来像这样：
public partial class MainPage: ContentPage
{
public MainPage ()
{
InitializeComponent ();
var map = new Map ()
{
MapType = MapType.Street,
IsShowingUser = true
};
var stack = new StackLayout {Spacing = 0};
stack.Children.Add (map);
Content = stack;
}
}
我在Xamarin.Android中的MainActivity类看起来像这样：
[Activity (Label = "ExampleGeolocation", Icon = "@ drawable / icon",
Theme = "@ style / MainTheme", MainLauncher = true,
ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation)]
public class MainActivity: global :: Xamarin.Forms.Platform.Android.FormsAppCompatActivity, ActivityCompat.IOnRequestPermissionsResultCallback
{
View layout;
const int RequestLocationId = 0;
readonly string [] PermissionsLocation = {Manifest.Permission.AccessCoarseLocation, Manifest.Permission.AccessFineLocation};
protected override void OnCreate (Bundle bundle)
{
TabLayoutResource = Resource.Layout.Tabbar;
ToolbarResource = Resource.Layout.Toolbar;
base.OnCreate (bundle);
global :: Xamarin.Forms.Forms.Init (this, bundle);
global :: Xamarin.FormsMaps.Init (this, bundle);
Plugin.CurrentActivity.CrossCurrentActivity.Current.Activity = this;
SetStatusBarColor (Android.Graphics.Color.Black);
LoadApplication (new App ());
}
public override async void OnRequestPermissionsResult (int requestCode, string [] permissions, [GeneratedEnum] Permission [] grantResults)
{
switch (requestCode)
{
case RequestLocationId:
{
if (grantResults [0] == Permission.Granted)
{
var snack = Snackbar.Make (layout, "Location Permission is Available.", Snackbar.LengthShort);
snack.Show ();
await GetLocationAsync ();
}
else
{
var snack = Snackbar.Make (layout, "Location Permission Denied", Snackbar.LengthShort);
snack.Show ();
}
}
break;
}
}
async Task TryGetLocationAsync ()
{
if ((int) Build.VERSION.SdkInt <23)
{
await GetLocationAsync ();
return;
}
await GetLocationPermissionAsync ();
}
async Task GetLocationPermissionAsync ()
{
const string permission = Manifest.Permission.AccessFineLocation;
if (CheckSelfPermission (permission) == Permission.Granted)
{
await GetLocationAsync ();
return;
}
if (ShouldShowRequestPermissionRationale (permission))
{
Snackbar.Make (layout, "You must allow the application to access your location options.", Snackbar.LengthIndefinite)
.SetAction ("OK", v => RequestPermissions (PermissionsLocation, RequestLocationId))
.Show();
return;
}
RequestPermissions (PermissionsLocation, RequestLocationId);
}
async Task GetLocationAsync ()
{
try
{
var locator = CrossGeolocator.Current;
}
catch (Exception e)
{
e.ToString ();
throw new NotImplementedException ();
}
}
};
使用Xamarin.Forms.Maps，Android的位置权限高于6.0
您编写了大量有关权限的代码但我无法找到您请求权限的位置，您需要在使用之前请求权限。
当您将IsShowingUser属性设置为true时，您应首先请求权限，这里有三个解决方案。
我注意到你在代码中使用PermissionsPlugin，如果你需要在PCL中请求此权限，你可以参考PermissionsPlugin official sample。
在MainActivity中添加此代码：
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Permission[] grantResults)
{
PermissionsImplementation.Current.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}
需要时请求权限：
try
{
var status = await CrossPermissions.Current.CheckPermissionStatusAsync(Permission.Location);
if (status != PermissionStatus.Granted)
{
if(await CrossPermissions.Current.ShouldShowRequestPermissionRationaleAsync(Permission.Location))
{
await DisplayAlert("Need location", "Gunna need that location", "OK");
}
var results = await CrossPermissions.Current.RequestPermissionsAsync(Permission.Location);
status = results[Permission.Location];
}
if (status == PermissionStatus.Granted)
{
//Permission granted, do what you want do.
}
else if(status != PermissionStatus.Unknown)
{
await DisplayAlert("Location Denied", "Can not continue, try again.", "OK");
}
}
catch (Exception ex)
{
//...
}
当您打开应用程序时，首先请使用MainActivity OnStart方法请求权限：
protected override void OnStart()
{
base.OnStart();
if (ContextCompat.CheckSelfPermission(this, permission) != Permission.Granted)
{
ActivityCompat.RequestPermissions(this, new String[] { Manifest.Permission.AccessCoarseLocation, Manifest.Permission.AccessFineLocation }, 0);
}
else
{
System.Diagnostics.Debug.WriteLine("Permission Granted!!!");
}
}
使用DependencyService在需要时请求许可，这里是与你读过的sample相关的tutorial。在此示例中，它在执行此行时请求权限：
buttonGetLocation.Click += async (sender, e) => await TryGetLocationAsync();
在Android内部添加此内容MainActiviy OnCreate（）
Plugin.CurrentActivity.CrossCurrentActivity.Current.Activity = this;
将此添加到android mainactivity：
public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Android.Content.PM.Permission[] grantResults)
{
Plugin.Permissions.PermissionsImplementation.Current.OnRequestPermissionsResult(requestCode, permissions, grantResults);
base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
}
然后此代码将起作用，提示用户获取位置权限。
var locator = CrossGeolocator.Current;
locator.DesiredAccuracy = 1000;
var position = await locator.GetPositionAsync(timeoutMilliseconds: 10000);
参考：
确保您已设置所有必要的权限。如果你想在Android上使用Xamarin.Forms.Maps，请确保你在项目的AndroidManifest.xml文件中设置了以下权限：
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
您还可以通过在Android项目上单击鼠标右键并选择Properties来设置权限。转到选项卡Android Manifest并标记所有必要的权限。
还要确保在应用程序标记中添加了以下两个语句：
<meta-data android:name="com.google.android.geo.API_KEY" android:value="ADD_YOUR_KEY_HERE" />
<meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" />
此视频可以帮助您获得xamarin表单https://www.youtube.com/watch?v=IWdpzpFChUQ的运行时权限