I am working on quiz app, I want that if user has answered the questions then after refreshing the app explanation should be expanded , i wrote this code which is not working, can anyone help me

import 'package:get/get.dart';

import 'package:shared_preferences/shared_preferences.dart';

import 'package:usml_question_of_day/models/categories_model.dart';

import 'package:usml_question_of_day/models/option_percentage_model.dart';

import 'package:usml_question_of_day/view/questionPage/service/question_service.dart';

class QuestionController extends GetxController with QuestionService {

RxBool isLoading = true.obs;

RxString selectedAnswerValue = "".obs;

RxBool isSelected = false.obs;

RxList<CategoryQuestions> allQuestions = <CategoryQuestions>[].obs;

RxList<String> questionCategoryName = <String>[].obs;

RxList<int> questionCategoryId = <int>[].obs;

RxInt questionIndex = 0.obs;

RxString categoryName = "".obs;

RxBool isSnackbarShown = false.obs;

SharedPreferences? _prefs;

Set<int> addedQuestionIds = <int>{}; // Track added question IDs

@override

void onInit() {

super.onInit();

_initializePreferences();

}

Future<void> _initializePreferences() async {

_prefs = await SharedPreferences.getInstance();

await fetchData(); // Fetch data before loading saved state

_loadSavedData();

}

void _loadSavedData() {

for (var question in allQuestions) {

final questionId = question.id!;

String? savedAnswer = _prefs?.getString('selectedAnswer_$questionId');

bool savedExplanationExpanded =

_prefs?.getBool('isExplanationExpanded_$questionId') ??

true; // Default to true

if (savedAnswer != null && savedAnswer.isNotEmpty) {

answeredQuestionId.add(questionId);

answeredSelectedAnswer.add(savedAnswer);

if (questionIndex.value == allQuestions.indexOf(question)) {

selectedAnswerValue.value = savedAnswer;

isSelected.value = true;

}

}

// Set isExplanationExpanded based on saved state, defaulting to true

question.isExplanationExpanded = savedExplanationExpanded;

}

}

void saveSelectedData(int questionId, String answer) {

_prefs?.setString('selectedAnswer_$questionId', answer);

_prefs?.setBool('isExplanationExpanded_$questionId',

allQuestions[questionIndex.value].isExplanationExpanded);

}

Future<void> fetchData() async {

isLoading.value = true;

allQuestions.clear();

addedQuestionIds.clear(); // Clear existing IDs before fetching new data

final dt = await getDataFromApi();

if (dt.categories != null) {

for (var element in dt.categories!) {

questionCategoryName.add(element.name!);

questionCategoryId.add(element.id!);

for (var question in element.categoryQuestions!) {

if (!addedQuestionIds.contains(question.id)) {

question.isExplanationExpanded =

true; // Initialize RxBool for explanation state

allQuestions.add(question);

addedQuestionIds.add(question.id!);

}

}

}

if (allQuestions.isNotEmpty) {

findCatName(0);

questionIndex.listen((p0) {

findCatName(p0);

// Update selected answer and explanation state for the new question index

selectedAnswerValue.value = "";

isSelected.value = false;

if (answeredQuestionId.contains(allQuestions[p0].id!)) {

selectedAnswerValue.value =

_prefs?.getString('selectedAnswer_${allQuestions[p0].id!}') ??

"";

isSelected.value = true;

}

allQuestions[p0].isExplanationExpanded = _prefs

?.getBool('isExplanationExpanded_${allQuestions[p0].id!}') ??

true; // Default to true

});

}

}

isLoading.value = false;

}

void findCatName(int idx) {

final catId = allQuestions[idx].categoryId;

for (int i = 0; i < questionCategoryId.length; i++) {

if (questionCategoryId[i] == catId) {

categoryName.value = questionCategoryName[i];

}

}

}

RxList<int> answeredQuestionId = <int>[].obs;

RxList<String> answeredSelectedAnswer = <String>[].obs;

RxBool shouldCheck = false.obs;

RxBool isExplanation = false.obs;

RxList<List<Percentage>> answeredPercentage = <List<Percentage>>[].obs;

RxBool isnAnswerSubmitted = false.obs;

Future<void> sendAnswer(String optId, String catId) async {

final dt = await submitAnswer(optId, catId);

if (dt.message != null) {

answeredPercentage.add(dt.percentage!);

isExplanation.value = true; // Expand explanation after submitting answer

_prefs?.setBool(

'isExplanationExpanded_${allQuestions[questionIndex.value].id}',

true); // Save explanation expanded state

allQuestions[questionIndex.value].isExplanationExpanded =

true; // Update local state

}

}

RxList<String> favIds = <String>[].obs;

Future<void> addToFav(String qstId, catId) async {

favIds.add(qstId);

await addToFavorites(qstId, catId);

}

bool isFav(String qstId) {

return favIds.contains(qstId);

}

}

I have used Sharedprefrences for storing the correct answer and user selected option