public async Task DownloadLesson(List <Lesson> ListLesson, string idLesson) { string nameLesson = null; //lưu tên Lesson để thông báo // Download Lesson foreach (var myLesson in ListLesson) { if (myLesson.Id.Equals(idLesson)) { nameLesson = myLesson.Name.Trim(); lessonDb = new LessonDatabaseAccess(); lessonDb.AddLesson(myLesson); break; } } RestQuestionService resQuestionService = new RestQuestionService(); List <Question> myLstQuestion = await resQuestionService.GetDataWithIDAsync(idLesson); // Lấy các câu hỏi có trong Lesson questionDb = new QuestionDatabaseAccess(); answerDb = new AnswerDatabaseAccess(); foreach (var myQuestion in myLstQuestion) { questionDb.AddQuestion(myQuestion); // Download Question RestAnswerService resAnswerService = new RestAnswerService(); List <Answer> myLstAnswer = await resAnswerService.GetDataWithIDAsync(myQuestion.QuestionID); // Lấy các câu trả lời có trong cầu hỏi foreach (var myAnswer in myLstAnswer) { answerDb.AddAnswer(myAnswer); //Download Answer } } DependencyService.Get <IMessage>().LongToast("Download " + nameLesson + " Completed"); }