//search by topic
        private async void searchByTopic()
        {
            LoadingOverlay.Instance.showLoading(this);
            if (!searchBar.Text.Equals(""))
            {
                WorkshopList          workshopList = new WorkshopList();
                List <SingleWorkshop> ab           = await workshopList.searchByTopic(searchBar.Text);

                this.showResultInTable(ab);
            }
        }
        //search by date
        private async void searchByDate()
        {
            LoadingOverlay.Instance.showLoading(this);
            if (!searchBar.Text.Equals(""))
            {
                WorkshopList workshopList = new WorkshopList();

                List <SingleWorkshop> ab = await workshopList.searchByStartDate(this.toDateFromNSDate(dateVC.selectedDate));

                this.showResultInTable(ab);
            }
        }