如何从另一个类触发有状态小部件中的函数当 onUnityAdsFinish 时？

问题描述

我在一个有状态小部件中有一个游戏屏幕，其中包含一个让玩家后退一步（撤消上一步）的功能。我想在 onUnityAdsFinish() 从另一个小部件运行时触发此函数。

这是 game.dart 上运行游戏的有状态小部件：

class GameScreen extends StatefulWidget {
  @override
  GameScreenState createState() => GameScreenState();
}

class GameScreenState extends State<GameScreen> with SingleTickerProviderStateMixin {

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        Container( 
            // game content here
        ),MaterialButton(
          child: Text("Tap Here to Watch Ad to Undo Move"),onpressed: () => unityBloc.showUnityAd(),// (side note: unityBloc is accessable because I have it declared as "final unityBloc = UnityBloc();" higher up the widget tree on app.dart.)
        ),],),}

  // This is the function I want to call after the ad is finished.
  void undoMove() {
    setState(() {
      // code to undo move
    });
  }
}

当按下按钮观看广告时，它会在 unity_bloc.dart 上调用我的 UnityBloc 类中的 showUnityAd() 函数：

import 'package:unity_ads_Flutter/unity_ads_Flutter.dart';

class UnityBloc with UnityAdsListener {
...
  showUnityAd() {
    UnityAdsFlutter.show('rewardedVideo').whenComplete(() => null);
  } // called when undo button is pressed on game.dart

  @override
  void onUnityAdsFinish(String placementId,FinishState result) {
    print("Finished $placementId with $result");
    // here is where I want to call the undoMove() function from game.dart
  }
}

广告显示完美，广告完成后 onUnityAdsFinish 中的打印语句会打印到控制台，但此时我不知道如何调用 undoMove。

我花了一整天的时间看教程和阅读有关回调和全局键等的 stackoverflows，但我仍然没有明白。

有人可以帮忙吗？当 onUnityAdsFinish() 在 unity_bloc.dart 上触发时，如何触发 game.dart 上的 undoMove() 函数？（或者是他们的另一种/更好的方式来做到这一点？）

谢谢！

解决方法

您可以在 UnityBloc 类中拥有一个保存函数的变量，并将 undoMove 方法传递给 showUnityAd 方法以将其分配给该变量，然后您可以在onUnityAdsFinish 方法。

所以 UnityBloc 变成了这个：

class UnityBloc with UnityAdsListener {
  void Function() doOnUnityAdsFinish;

  ...

  showUnityAd({@required unityAdsFinishFunction}) {
    ...
    doOnUnityAdsFinish = unityAdsFinishFunction;
  } // called when undo button is pressed on game.dart

  @override
  void onUnityAdsFinish(String placementId,FinishState result) {
   ...
   doOnUnityAdsFinish?.call(); //Only calls if the function is not null
  }
}

你可以在 MaterialButton 的 onPressed 中这样：

 MaterialButton(
          child: Text("Tap Here to Watch Ad to Undo Move"),onPressed: () => unityBloc.showUnityAd(unityAdsFinishFunction: undoMove ),),

最简单的方法是全局/静态变量（回调）或 ValueNotifier/Stream。也许，更简洁的方法是一些具有依赖注入功能的包，例如 (get,get_it)。

class UnityBloc with UnityAdsListener {
  /// pass a callback into the constructor.
  /// Function<String,FinishState> onAdCompleted ;
  /// UnityBloc([this.onAdCompleted]);

  /// easier approach,not very "flexible".
  static Function<String,FinishState> onAdCompleted ;

  showUnityAd() {
    UnityAdsFlutter.show('rewardedVideo').whenComplete(() => null);
  } // called when undo button is pressed on game.dart

  @override
  void onUnityAdsFinish(String placementId,FinishState result) {
    onAdCompleted?.call(placementId,result); 
    // here is where I want to call the undoMove() function from game.dart
  }
}


class GameScreenState extends State<GameScreen> with SingleTickerProviderStateMixin {

  @override
  void initState(){
     super.initState();
     UnityBloc.onAdCompleted = _onAddCompleted;
  }

  @override
  void dispose(){
     super.dispose();
     if( UnityBloc.onAdCompleted == _onAddCompleted) {
         UnityBloc.onAdCompleted = null;
     }
  }

  void _onAddCompleted(String placementId,FinishState result) 
    => print("Finished $placementId with $result"); 

  @override
  Widget build(BuildContext context) {
    return Column(
      children: <Widget>[
        Container( 
            // game content here
        ),MaterialButton(
          child: Text("Tap Here to Watch Ad to Undo Move"),onPressed: () => unityBloc.showUnityAd(),// (side note: unityBloc is accessable because I have it declared as "final unityBloc = UnityBloc();" higher up the widget tree on app.dart.)
        ),],}

  // This is the function I want to call after the ad is finished.
  void undoMove() {
    setState(() {
      // code to undo move
    });
  }
}

dart unityads