如何在 dart flutter 中返回两个字符串值

Question

I am working on my flutter project where I want to use sharedpreferences. Look at the code below:

Future<String?> getCredentials() async {
   final localStorage = await SharedPreferences.getInstance();
   final email = localStorage.getString('email');
   final password = localStorage.getString('password');
   return email, password;
}

This is my getCredentials funtion I want this function to return email and password as different parameters but dart doesn't allow me can you please help me How can I do it?

Whole SharedPreference Code:

import 'package:shared_preferences/shared_preferences.dart';

class sharedPreference {
  Future<String?> saveCredentials({
    required String email,
    required String password,
  }) async {
    final localStorage = await SharedPreferences.getInstance();
    await localStorage.setString('email', email);
    await localStorage.setString('password', password);
  }

  Future<String?> getCredentials() async {
    final localStorage = await SharedPreferences.getInstance();
    final email = localStorage.getString('email');
    final password = localStorage.getString('password');
    return email, password;
  }
}

Answer 1

Just create class. You can even add methods to Credentials later. Like secure compare to compare passwordHash with constant time.

class Credentials {
  Credentials(this.email, this.passwordHash);

  final String email;
  final String passwordHash;
}

Future<Credentials> getCredentials() async {
   final localStorage = await SharedPreferences.getInstance();
   final email = localStorage.getString('email');
   final passwordHash = localStorage.getString('passwordHash');
   return Credentials(email, passwordHash));
}

Edit use crypto to get hash of password:

import 'dart:convert';
import 'package:crypto/crypto.dart';

String getHash(String plainPassword) {
    return sha256.convert(utf8.encode(plainPassword)).toString();
}

Answer 2

change return type String to Map<String,dynamic>

Future<Map<String,dynamic>> getCredentials() async {
   final localStorage = await SharedPreferences.getInstance();
   final email = localStorage.getString('email');
   final password = localStorage.getString('password');
   return {
'email':email,
'password':password

};
}