// open an existing zip file async void _btnOpen_Click(object sender, RoutedEventArgs e) { try { var picker = new Windows.Storage.Pickers.FileOpenPicker(); picker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.DocumentsLibrary; picker.FileTypeFilter.Add(".xlsx"); picker.FileTypeFilter.Add(".xls"); var file = await picker.PickSingleFileAsync(); if (file != null) { // step 1: create a new workbook _book = new C1XLBook(); // step 2: load existing file var fileFormat = FileFormat.OpenXml; await _book.LoadAsync(file, fileFormat); // step 3: allow user to save the file _tbContent.Text = string.Format(Strings.OpenTip, _book.Sheets[0].Name); RefreshView(); } } catch (Exception x) { _tbContent.Text = string.Format(Strings.SaveAndOpenException, x.Message); } }