Flutter -如何在非异步方法中从共享首选项中获取值

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('SharedPreferences Example'),
        ),
        body: Center(
          child: ElevatedButton(
            onPressed: () {
              // 在非异步方法中调用
              String? value = getValueFromSharedPreferences();
              if (value != null) {
                print('Value from SharedPreferences: $value');
              } else {
                print('Failed to get value from SharedPreferences');
              }
            },
            child: Text('Get Value'),
          ),
        ),
      ),
    );
  }

  String? getValueFromSharedPreferences() {
    // 使用Future来处理异步操作
    return Future<String?>.sync(() async {
      final prefs = await SharedPreferences.getInstance();
      return prefs.getString('myKey');
    }).then((value) {
      return value;
    }).catchError((error) {
      print('Error: $error');
      return null;
    });
  }
}