问Xamarin Android请求运行时权限不起作用

EN

 if (!(CheckPermissionGranted(Manifest.Permission.AccessCoarseLocation) &&
            CheckPermissionGranted(Manifest.Permission.AccessFineLocation)))
        {
            RequestLocationPermission();
        }
        else
        {
            InitializeLocationManager();
        }
        InitPageWidgets();

 [Export]
    public bool CheckPermissionGranted(string Permissions)
    {
        // Check if the permission is already available.
        if (ActivityCompat.CheckSelfPermission(this, Permissions) != Permission.Granted)
        {
            return false;
        }
        else
        {
            return true;
        }


    }

  private void RequestLocationPermission()
    {
        if (ActivityCompat.ShouldShowRequestPermissionRationale(this, Manifest.Permission.AccessFineLocation))
        {
            // Provide an additional rationale to the user if the permission was not granted
            // and the user would benefit from additional context for the use of the permission.
            // For example if the user has previously denied the permission.
            ActivityCompat.RequestPermissions(this, PermissionsLocation, REQUEST_LOCATION);

        }
        else
        {
            // Camera permission has not been granted yet. Request it directly.
            ActivityCompat.RequestPermissions(this, PermissionsLocation, REQUEST_LOCATION);
        }
    }

[Activity(Label = "@string/app_name", Theme = "@style/AppTheme.NoActionBar", MainLauncher = true, ScreenOrientation = ScreenOrientation.Landscape)]
public class MainLoaderActivity : AppCompatActivity {

    private const string LOG_TAG = "CAMERA2_LOG";        
    private const int PERMISSION_REQUEST_CODE_CAMERA_USAGE = 4500;  // Arbitrary number to identify our permissions required for camera app usage
    private Button btnLoadCameraActivity;

    protected override void OnCreate(Bundle savedInstanceState) {
        base.OnCreate(savedInstanceState);
        SetContentView(Resource.Layout.main_loader);
        btnLoadCameraActivity = FindViewById<Button>(Resource.Id.btnLoadCameraActivity);
        btnLoadCameraActivity.Click += btnLoadCameraActivity_Click;
    }

    private void btnLoadCameraActivity_Click(object sender, EventArgs e) {
        // Using the camera on Android 6.0 and later requires a run-time permissions granting by the user.
        // So, check to see if user manually enabled in Settings, or previously was prompted in this app and was granted access.  If not, we'll prompt them...

        if (CheckSelfPermission(Android.Manifest.Permission.Camera) == Permission.Granted && 
            CheckSelfPermission(Android.Manifest.Permission.WriteExternalStorage) == Permission.Granted) {
            // We have both permissions necessary to run the Camera interface...
            StartActivity(typeof(CameraActivity));
            return;
        }

        // If we get here, at least one of the required permissions hasn't been approved, so find out which one and request accordingly...
        var listPermissions = new System.Collections.Generic.List<string>();

        // Build array of permissions needed for Camera usage
        if (CheckSelfPermission(Android.Manifest.Permission.Camera) != Permission.Granted) {
            Log.Warn(LOG_TAG, "CheckSelfPermission(Camera) not yet granted - will prompt user for permission");
            listPermissions.Add(Android.Manifest.Permission.Camera);
        }
        if (CheckSelfPermission(Android.Manifest.Permission.WriteExternalStorage) != Permission.Granted) {
            Log.Warn(LOG_TAG, "CheckSelfPermission(WriteExternalStorage) not yet granted - will prompt user for permission");
            listPermissions.Add(Android.Manifest.Permission.WriteExternalStorage);
        }

        // Make the request with the permissions needed...and then check OnRequestPermissionsResult() for the results
        RequestPermissions(listPermissions.ToArray(), PERMISSION_REQUEST_CODE_CAMERA_USAGE);
    }

    public override void OnRequestPermissionsResult(int requestCode, string[] permissions, Android.Content.PM.Permission[] grantResults) {
        Log.Info(LOG_TAG, $"OnRequestPermissionsResult(requestCode={requestCode} - Permissions Count={permissions.Length} - GrantResults Count={grantResults.Length})");
        switch (requestCode) {
            // To use the camera, the user must grant privs to the Camera as well as writing to external storage, so this case checks both
            case PERMISSION_REQUEST_CODE_CAMERA_USAGE: {                    
                for (var i = 0; i < permissions.Length; i++) {
                    Log.Info(LOG_TAG, $"Checking permission for {permissions[i]}...");
                    if (grantResults[i] != Permission.Granted) {
                        Log.Info(LOG_TAG, $"Permission Denied for {permissions[i]}!");
                        Toast.MakeText(this, "You must approve all permissions prompted to use the camera.", ToastLength.Long).Show();
                        return;
                    }
                    Log.Info(LOG_TAG, $"Permission Granted for {permissions[i]}.");
                }
                // If we get here then all the permissions we requested were approved and we can now load the Camera interface
                StartActivity(typeof(CameraActivity));
                break;
            }
        }
    }

}