private async void ContentDialog_PrimaryButtonClick(ContentDialog sender, ContentDialogButtonClickEventArgs args) { var sESSDATA = ApplicationData.Current.LocalSettings.Values["biliUserSESSDATA"] as string; var list = new List <BiliVideoInfo>(); foreach (var item in vm.VideoList) { if (item.ToDownload == false) { continue; } list.Add(item.Info); } if (list.Count < 1) { PrimaryButtonText = "请选择至少一个视频"; await Task.Delay(2000); if (PrimaryButtonText == "请选择至少一个视频") { PrimaryButtonText = "下载所选项"; } return; } if (this.qualityComboBox.SelectedValue == null) { PrimaryButtonText = "请选择清晰度"; await Task.Delay(2000); if (PrimaryButtonText == "请选择清晰度") { PrimaryButtonText = "下载所选项"; } return; } this.needToClose = true; var quality = (int)this.qualityComboBox.SelectedValue; try { await DownloadHelper.CreateDownloadsAsync(list, quality, sESSDATA, XamlRoot); } catch (DirectoryNotFoundException ex) { var dialog = new ExceptionDialog(ex.Message, XamlRoot); _ = await dialog.ShowAsync(); } catch (ParsingVideoException ex) { var dialog = new ErrorDialog(ex.Message, XamlRoot); var result = await dialog.ShowAsync(); if (result == ContentDialogResult.Primary) { MainPage.NavView.SelectedItem = MainPage.NavViewItems[2]; MainPage.ContentFrame.Navigate(typeof(UserPage)); } } }