Flutter: Fatal Error: Callback lookup failed! (with audioplayers package)

Question

以下代码片段是点击按钮时会发出一声短促的哔声：

FlatButton(
  onPressed: () => {
    final player = new AudioCache();
    player.play('note1.wav');
  }
  child: Text('Click to ding!'),
),

我面临的问题是每当我单击此按钮时，虽然声音播放正确，但我在终端中收到此错误：flutter: Fatal Error: Callback lookup failed! 我想知道它是什么以及我应该做什么？

我检查了 package's issue page 但没有发现任何有用的信息。

谢谢

Answer 1

我遇到了同样的问题，所以这适用于我的游戏代码，我希望这对你有用，首先，像这样创建一个控制器 Class：

import 'package:audioplayers/audio_cache.dart';
import 'package:audioplayers/audioplayers.dart';

void audioPlayerHandler(AudioPlayerState value) => print('state => $value');

class GameController {

  static AudioPlayer audioPlayer = AudioPlayer();
  static AudioCache audioCache = AudioCache();

  static void play(String sound) {
    if (!kIsWeb && Platform.isIOS) {
      audioPlayer.monitorNotificationStateChanges(audioPlayerHandler);
    }
    audioCache.play(sound);
  }
}

然后通过这种方式使用您的代码：

FlatButton(
  onPressed: () => {
    GameController.play('note1.wav');
  }
  child: Text('Click to ding!'),
),

Answer 2

看起来像是“致命错误：回调查找失败！”的错误。如果未通过 monitorNotificationStateChanges.

定义回调方法，则会打印在日志中

By reading the source code好像没有发生过

但避免它的一种方法确实是设置回调，并且必须在外部您的 class 定义它，如下所示：

import 'package:audioplayers/audioplayers.dart';

class YourStatefulWidget extends StatefulWidget {
  @override
  _YourStatefulWidgetState createState() => _YourStatefulWidgetState();
}

class _YourStatefulWidgetState extends State<YourStatefulWidget> {
  ...

  @override
  void initState() {
    super.initState();

    if (Platform.isIOS) {
      // to avoid getting "Fatal Error: Callback lookup failed!"
      audioPlayer.monitorNotificationStateChanges(audioPlayerHandler);    
    }
  }

  ...
}

// must be defined globally
void audioPlayerHandler(AudioPlayerState value) => null;

Flutter: Fatal Error: Callback lookup failed! (with audioplayers package)

Flutter: Fatal Error: Callback lookup failed! (with audioplayers package)

flutter

dart

flutter-dependencies

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