Question

我是新手。我正在制作一个应用程序，该应用程序在首次使用该应用程序时会在第一个屏幕中输入电话号码。从下一次开始，我希望应用程序跳过第一个屏幕，直接转到下一个屏幕。但是我无法实现此功能。请帮忙。谢谢。

import 'package:shared_preferences/shared_preferences.dart';

class PrefShare {
  String mob;
  bool isNew;

  Future<String> spNumberSetter(String no) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setString('phoneNumber', no);
  }

  Future<String> spNumberGetter() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    mob = prefs.getString('phoneNumber');
  }

  Future<bool> spAppNew() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setBool('isLoggedIn', true);
  }

  Future<bool> spAppGetter() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    isNew = prefs.getBool('isLoggedIn');
  }
}


//main
import 'package:emergency_messaging/button_screen.dart';
import 'package:flutter/material.dart';
import 'prefs.dart';

PrefShare prefShare = PrefShare();

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  prefShare.spAppGetter();
  bool status = prefShare.isNew ?? false;
  prefShare.spAppNew();
  runApp(
    MaterialApp(home: status == true ? ButtonScreen() : Home()),
  );
}

class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {
  @override
  Widget build(BuildContext context) {
    String phoneNo;
    return SafeArea(
      child: Scaffold(
        backgroundColor: Color(0xff9ad3bc),
        floatingActionButton: FloatingActionButton(
          backgroundColor: Colors.black,
          child: Icon(
            Icons.arrow_forward,
            color: Color(0xff9ad3bc),
          ),
          onPressed: () {
            showDialog(
              context: context,
              builder: (context) {
                return AlertDialog(
                  title: Text("Confirmation"),
                  content: SingleChildScrollView(
                    child: ListBody(
                      children: <Widget>[
                        Text("The phone number entered is: $phoneNo"),
                      ],
                    ),
                  ),
                  actions: <Widget>[
                    FlatButton(
                      child: Text("Cancel"),
                      onPressed: () {
                        Navigator.pop(context);
                      },
                    ),
                    FlatButton(
                      child: Text("Continue"),
                      onPressed: () {
                        prefShare.spNumberSetter(phoneNo);
                        Navigator.push(
                            context,
                            MaterialPageRoute(
                                builder: (context) => ButtonScreen()));
                      },
                    ),
                  ],
                );
              },
            );
          },
        ),
        body: Padding(
          padding: EdgeInsets.all(8.0),
          child: Column(
            children: [
              SizedBox(
                height: 150.0,
              ),
              TextField(
                  style: TextStyle(color:  Colors.black,),
                  decoration: InputDecoration(

                    hintText: "Your emergency contact number",
                    hintStyle: TextStyle(color:  Colors.black,),
                    enabledBorder: UnderlineInputBorder(
                      borderSide: BorderSide(color:  Colors.black,),
                    ),
                    focusedBorder: UnderlineInputBorder(
                      borderSide: BorderSide(color:  Colors.black,),
                    ),
                  ),
                  keyboardType: TextInputType.phone,
                  autofocus: true,
                  cursorColor: Colors.black,
                  onChanged: (text) {
                    phoneNo = text;
                  },
                ),

            ],
          ),
        ),
      ),
    );
  }
}

Answer 1

我认为您的问题是从这里引起的：prefShare.spAppGetter();

由于 Future<bool> spAppGetter() async {...}是一个返回未来的异步函数，因此您应使用await进行调用，这样可以确保在调用bool status = prefShare.isNew ?? false;之前spAppGetter已完成。为此，您还应该将主要功能标记为异步。然后，您的主要功能将如下所示：

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await prefShare.spAppGetter();
  bool status = prefShare.isNew ?? false;
  prefShare.spAppNew();
  runApp(
    MaterialApp(home: status == true ? ButtonScreen() : Home()),
  );
}

Answer 2

您没有使用getBool（“ isLoggedIn”）的状态

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  prefShare.spAppGetter();// it will actually tell you that you if user logged in or not
  bool status = prefShare.isNew ?? false;
  prefShare.spAppNew(); // this should be where the user once logged in.
  runApp(
    MaterialApp(home: status == true ? ButtonScreen() : Home()),
  );
}

所以应该是这样

void main() async{
  WidgetsFlutterBinding.ensureInitialized();
    bool status =await SharedPreferences.getInstance().getBool('isLoggedIn');
    runApp(
    MaterialApp(home: status == true ? ButtonScreen() : Home()),
  );
}

并在此处保存保存登录状态

  FlatButton(
                          child: Text("Continue"),
                          onPressed: () {
                            prefShare.spNumberSetter(phoneNo);
SharedPreferences.getInstance().setBool('isLoggedIn');
                            Navigator.push(
                                context,
                                MaterialPageRoute(
                                    builder: (context) => ButtonScreen()));
                          },
                        ),

您也应该研究命名约定

Flutter应用无法跳过旧用户的介绍屏幕

2 个答案: