private async Task QueryTopics()
        {            
            if(page == 1)
            {
                if(TopicItems == null)
                {
                    TopicItems = new ObservableCollection<TopicItem>();
                }
                else
                {
                    TopicItems.Clear();
                }
            }

            UserContentProvider user = new UserContentProvider();
            List<DiscoverResult> reuslt = await user.QueryTopic(TypeSelectedItem.Type, page, GlobalValue.CurrentUserContext.UserId, GlobalValue.CurrentUserContext.MobileToken);

            reuslt.ForEach(x => TopicItems.Add(ConvertToTopicItem(x)));

            page++;
        }