如何以无法在 Flutter 中异步的方法从共享首选项中获取首选项？

Question

我想获得共享pref的bool来决定应该加载哪个Widget，但该方法不能是异步的，也不能是bool，因为它不允许"等待"；值。我试过修复它，但大部分都失败了，因为"；家；无法接收未来的小部件。。。，有没有其他方法可以让我做到这一点？

void main() => runApp(MyApp());
setloginbool() async{
SharedPreferences prefs = await SharedPreferences.getInstance();
prefs.setBool("savelogin", true);
}
Future<bool> getloginbool() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
bool savelogin = prefs.getBool("savelogin") ?? false;
return savelogin;
}

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'KHS Plan',
theme: (ThemeData(
textTheme: const TextTheme(
bodyText1: TextStyle(fontSize: 14)
)
)),
home: checkifpassword(),
);
}
}
Widget checkifpassword() {
bool s = await getloginbool();
if(s){
return const Login();
} else {
return const MyHomePage();
}
}

//This does not work as well
checkifpassword() async {
bool s = await getloginbool();
if(s){
return const Login();
} else {
return const MyHomePage();
}
}

Answer 1

您可以在Home上使用FutureBuilder

Future<bool> checkifpassword() async {
//perfrom your async operation and return bool
return await Future.delayed(Duration(seconds: 2), () {
return true;
});
}

和home

home: FutureBuilder<bool>(
future: checkifpassword(),
builder: (context, snapshot) {
if (snapshot.hasData) {
if (snapshot.data!) {// for true
return Login();;
} else return MyHomePage();
}
/// check others state
return Scaffold(
body: Center(
child: CircularProgressIndicator(),
),
);
},
)