I'm trying introduction_screen 2.1.0 to show intro screen. I imported it and declared import:

import 'package:introduction_screen/introduction_screen.dart';

But when I call IntroductionScreen(), an error occurred.

_AssertionError ('package:introduction_screen/src/introduction_screen.dart': Failed assertion: line 209 pos 16: '(showNextButton && next != null) || !showNextButton': is not true.)

I referenced some examples and wrote this simple code:

class Intro extends StatefulWidget {
  const Intro({Key? key}) : super(key: key);

  @override
  _Intro createState() => _Intro();
}

class _Intro extends State<Intro> {
  List<PageViewModel> getPages() {
    return [
      PageViewModel(
          image: null,
          title: "Live Demo page 1",
          body: "Welcome to Proto Coders Point",
          footer: Text("Footer Text here "),
          decoration: const PageDecoration(
            pageColor: Colors.blue,
          )),
    // .................
    ];
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text("Example"),
        ),
        body: SafeArea(
            child: IntroductionScreen(              // ERROR!!
          globalBackgroundColor: Colors.white,
          pages: getPages(),
          showNextButton: true,
          showSkipButton: true,
          skip: Text("Skip"),
          done: Text("Got it "),
          onDone: () {},
        )));
  }
}

As I said before, IntroductionScreen() is an issue.

I imported pub correctly, looks my environment is okay.

[√] Flutter (Channel beta, 2.6.0-5.2.pre, on Microsoft Windows [Version 10.0.22000.258], locale ja-JP)
    • Flutter version 2.6.0-5.2.pre at D:\src\flutter_windows_2.5.0-stable\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 400608f101 (5 weeks ago), 2021-09-15 15:50:26 -0700
    • Engine revision 1d521d89d8
    • Dart version 2.15.0 (build 2.15.0-82.2.beta)

[√] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at D:\Android
    • Platform android-30, build-tools 29.0.3
    • Java binary at: D:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 11.0.8 10-b944.6842174)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Android Studio (version 4.2)
    • Android Studio at D:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 11.0.8 10-b944.6842174)

[√] VS Code (version 1.61.2)
    • VS Code at C:\Users\yukik\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.27.0

[√] Connected device (3 available)
    • Android SDK built for x86 (mobile) • emulator-5554 • android-x86    • Android 10 (API 29) (emulator)
    • Chrome (web)                       • chrome        • web-javascript • Google Chrome 95.0.4638.54
    • Edge (web)                         • edge          • web-javascript • Microsoft Edge 95.0.1020.30

• No issues found!

CodePudding user response：

From the documentation:

Define Next button (Widget), by adding next: Text('Next') This param is required, except if you set showNextButton: false