protected override void OnNavigatedTo(NavigationEventArgs e)
        {
            _user = (UwpUser)e.Parameter;
            MapHandler.DrawUser(MyMap, _user, false, false);
            MapHandler.Center(MyMap, _user.Location);
            GeofenceMonitor.Current.GeofenceStateChanged += CurrentOnGeofenceStateChanged;

            var refreshRequest = JsonConvert.SerializeObject(new RefreshRequest {
                user = _user.User
            });

            var packet = new Packet {
                PacketType = EPacketType.RefreshRequest, Payload = refreshRequest
            };

            TcpClient.DoRequest(packet, ResponseCallback);

            StartTimer();
        }
        // ff de t weer hoofdletter
        //private void Starttimer()
        //{
        //    TimeSpan delay = TimeSpan.FromSeconds(10);

        //    ThreadPoolTimer.CreatePeriodicTimer(
        //        source =>
        //        {
        //            var refreshRequest = JsonConvert.SerializeObject(new RefreshRequest { user = _user.User });

        //            var packet = new Packet { PacketType = EPacketType.RefreshRequest, Payload = refreshRequest };

        //            TcpClient.DoRequest(packet, ResponseCallback);
        //        }, delay);

        //}

        private async void ResponseCallback(Packet packet)
        {
            if (packet.Payload != null)
            {
                var friends = JsonConvert.DeserializeObject <AllFriendsResponse>(packet.Payload);

                await Dispatcher.RunAsync(CoreDispatcherPriority.High, () =>
                {
                    GeofenceMonitor.Current.Geofences.Clear();
                    MapHandler.DrawUser(MyMap, _user, true, false);

                    foreach (User u in friends.friends)
                    {
                        UwpUser friend = new UwpUser(u, "");
                        AddGeofence(friend.Location, friend.User.UserName, 20);
                        MapHandler.DrawUser(MyMap, friend, true, true);
                    }
                    Debug.WriteLine("update friend");
                });
            }
        }