display of sharedpreference in textfield flutter - flutter

Question

I have a textfield that I will use with sharedpreference to store and pass the value into another page. so far it works.
how to make so that when I return on the page of my textfield there is my value which remains which remains in the textfield?
as it will be a page for setting parameters, when I come back to it, the elements in sharedpreferences will have to remain displayed like this when we modify 1 element, it keeps the others too.
Thanks in advance.
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
class TestPage extends StatefulWidget {
const TestPage({Key? key}) : super(key: key);
#override
State<TestPage> createState() => _TestPageState();
}
class _TestPageState extends State<TestPage> {
final _pricesController = TextEditingController();
final Future<SharedPreferences> _prefs = SharedPreferences.getInstance();
late Future<String> _prix;
Future<void> _voirLePrix() async {
final SharedPreferences prefs = await _prefs;
final String _pricesController =
(prefs.getString('saisie') ?? _prix.toString());
setState(() {
_prix = prefs.setString('saisie', _pricesController).then((bool success) {
return _pricesController;
});
});
}
#override
void initState() {
super.initState();
_voirLePrix();
_prix = _prefs.then((SharedPreferences prefs) {
return prefs.getString('saisie') ?? '';
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('test saisie')),
body: Center(
child: FutureBuilder<String>(
future: _prix,
builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.waiting:
return const CircularProgressIndicator();
default:
if (snapshot.hasError) {
return Text('erreur: ${snapshot.error}');
} else {
return TextField(
controller: _pricesController,
autofocus: false,
decoration: const InputDecoration(
//hintText: 'saisir un prix',
border: OutlineInputBorder(),
),
);
}
}
},
),
),
floatingActionButton: FloatingActionButton(
onPressed: _voirLePrix,
child: const Icon(Icons.add),
),
);
}
}