Unity中AdMob激励广告奖励堆叠问题及解决方法咨询

问题核心：每次调用showRewarded时，都会重复给rewardedAd.OnUserEarnedReward绑定新的匿名委托，但从未执行解绑操作。多次调用后，这个事件会积累多个委托实例，当用户获得奖励时，所有绑定过的委托都会触发，导致奖励次数1、2、3...逐次递增。

快速修复方案 #

方案1：使用命名方法，绑定前先解绑 #

把匿名委托改为命名方法，每次绑定前先移除旧的事件绑定，确保事件上始终只有一个委托：

private Action<bool> _currentRewardCallback;

public void showRewarded(Action<bool> giveReward)
{
    _currentRewardCallback = giveReward;
    
    if (rewardedAd.IsLoaded())
    {
        // 先移除之前的绑定，避免堆叠
        rewardedAd.OnUserEarnedReward -= OnUserEarnedReward;
        rewardedAd.OnUserEarnedReward += OnUserEarnedReward;
        
        rewardedAd.Show();
    }
    else
    {
        giveReward(false);
    }

    requestRewarded();
}

private void OnUserEarnedReward(object sender, Reward reward)
{
    // 触发回调后立刻解绑
    rewardedAd.OnUserEarnedReward -= OnUserEarnedReward;
    _currentRewardCallback?.Invoke(true);
    _currentRewardCallback = null;
}

方案2：绑定一次性委托，执行后自动解绑 #

用临时变量保存匿名委托，在委托内部先解绑自己再执行奖励逻辑：

public void showRewarded(Action<bool> giveReward)
{
    if (rewardedAd.IsLoaded())
    {
        EventHandler<Reward> rewardHandler = null;
        rewardHandler = delegate(object sender, Reward reward)
        {
            // 先解绑自己，防止重复执行
            rewardedAd.OnUserEarnedReward -= rewardHandler;
            giveReward(true);
        };
        
        rewardedAd.OnUserEarnedReward += rewardHandler;
        rewardedAd.Show();
    }
    else
    {
        giveReward(false);
    }

    requestRewarded();
}

更优的实现方式 #

上面的修复是应急方案，更规范的做法是统一管理广告生命周期，事件仅绑定一次，从根源避免委托堆叠：

public class AdsController : MonoBehaviour
{
    public static AdsController Instance;
    
    private RewardedAd _rewardedAd;
    private Action<bool> _pendingRewardCallback;
    private bool _isRequestingAd;

    private void Awake()
    {
        Instance = this;
        InitializeRewardedAd();
    }

    // 初始化广告，仅绑定一次所有生命周期事件
    private void InitializeRewardedAd()
    {
        _rewardedAd = new RewardedAd("你的AdMob广告ID");
        
        _rewardedAd.OnAdLoaded += OnRewardedAdLoaded;
        _rewardedAd.OnAdFailedToShow += OnRewardedAdShowFailed;
        _rewardedAd.OnUserEarnedReward += OnUserEarnedReward;
        
        RequestRewardedAd();
    }

    public void ShowRewarded(Action<bool> onRewardCompleted)
    {
        _pendingRewardCallback = onRewardCompleted;
        
        if (_rewardedAd.IsLoaded())
        {
            _rewardedAd.Show();
        }
        else
        {
            onRewardCompleted?.Invoke(false);
            // 未加载完成时，仅在未请求广告时发起请求
            if (!_isRequestingAd) RequestRewardedAd();
        }
    }

    private void RequestRewardedAd()
    {
        if (_isRequestingAd) return;
        
        _isRequestingAd = true;
        AdRequest adRequest = new AdRequest.Builder().Build();
        _rewardedAd.LoadAd(adRequest);
    }

    private void OnRewardedAdLoaded(object sender, EventArgs e)
    {
        _isRequestingAd = false;
    }

    private void OnRewardedAdShowFailed(object sender, AdErrorEventArgs e)
    {
        _pendingRewardCallback?.Invoke(false);
        _pendingRewardCallback = null;
        RequestRewardedAd();
    }

    private void OnUserEarnedReward(object sender, Reward e)
    {
        _pendingRewardCallback?.Invoke(true);
        _pendingRewardCallback = null;
        RequestRewardedAd();
    }

    // 销毁时清理资源，避免内存泄漏
    private void OnDestroy()
    {
        _rewardedAd.OnAdLoaded -= OnRewardedAdLoaded;
        _rewardedAd.OnAdFailedToShow -= OnRewardedAdShowFailed;
        _rewardedAd.OnUserEarnedReward -= OnUserEarnedReward;
        _rewardedAd.Destroy();
    }
}

这种方式的优势：

• 事件仅绑定一次，彻底避免委托堆叠问题
• 统一管理广告的加载、展示失败、奖励发放逻辑
• 避免重复请求广告，减少无效请求
• 销毁时自动清理资源，防止内存泄漏

内容的提问来源于stack exchange，提问作者SengunSipahi