SharedPreferences en Flutter: ejercicio resuelto para guardar ajustes

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

void main() => runApp(const MaterialApp(home: PreferencesPage()));

class PreferencesPage extends StatefulWidget {
  const PreferencesPage({super.key});

  @override
  State<PreferencesPage> createState() => _PreferencesPageState();
}

class _PreferencesPageState extends State<PreferencesPage> {
  final ctrl = TextEditingController();
  String savedName = '';

  @override
  void initState() {
    super.initState();
    loadName();
  }

  Future<void> loadName() async {
    final prefs = await SharedPreferences.getInstance();
    setState(() => savedName = prefs.getString('name') ?? '');
  }

  Future<void> saveName() async {
    final prefs = await SharedPreferences.getInstance();
    await prefs.setString('name', ctrl.text.trim());
    await loadName();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('SharedPreferences')),
      body: Padding(
        padding: const EdgeInsets.all(16),
        child: Column(
          children: [
            TextField(controller: ctrl, decoration: const InputDecoration(labelText: 'Nombre')),
            const SizedBox(height: 12),
            ElevatedButton(onPressed: saveName, child: const Text('Guardar')),
            const SizedBox(height: 16),
            Text('Guardado: $savedName'),
          ],
        ),
      ),
    );
  }
}