private void CallBackForUserDetails(User user) { Device.BeginInvokeOnMainThread(() => { var record = AvailableDevices.Where(a => a.IPAddress == user.IPAddress); if (record.Any()) { AvailableDevices.Remove(record.First()); } AvailableDevices.Add(new User() { IPAddress = user.IPAddress, Name = user.Name }); }); }