private void OnUserTapped(User user)
 {
     Messenger.Default.Send(new SetUserModelMessage {
         User = user
     });
     _customNavigationService.Navigate(typeof(UserPage));
 }
 private void OnSelectActivity(SelectionChangedEventArgs obj)
 {
     if (obj.AddedItems.Count > 0)
     {
         var activity = obj.AddedItems[0] as Activity;
         ServiceLocator.Current.GetInstance <ActivityViewModel>().Activity = activity;
         _customNavigationService.Navigate(typeof(ActivityPage));
     }
 }