Google Admob 多重奖励视频

Question

我有一个 Unity 游戏。我使用 3 个 RewardedAd（广告 ID 分开，以跟踪用户使用的是哪个奖励广告）。工作完美。 现在我想到了加载奖励视频的 UI 页面之一，我在同一个 UI 页面上添加了另一个 但是现在，当我打开奖励视频时，应用程序崩溃了。 我在应用程序启动时加载广告。

MobileAdsEventExecutor.ExecuteInUpdate(() =>
        {
            this.RewardedAd1 = RequestAndLoadRewardedAd(nameof(RewardedAdTypes.ad1));
            this.RewardedAd2 = RequestAndLoadRewardedAd(nameof(RewardedAdTypes.ad2));
            this.RewardedAd3 = RequestAndLoadRewardedAd(nameof(RewardedAdTypes.ad3));
            this.RewardedAd4 = RequestAndLoadRewardedAd(nameof(RewardedAdTypes.ad4));
        });

public RewardedAd RequestAndLoadRewardedAd(string place)
    {
        string adUnitId = "";

#if UNITY_ANDROID
        if (place.Equals(nameof(RewardedAdTypes.ad1)))
        {
            adUnitId = Constants.DEBUG_ADS ? TEST_ANDROID_REWARDED_AD : ANDROID_REWARDED_AD_1;
        }
        else if (place.Equals(nameof(RewardedAdTypes.ad2)))
        {
            adUnitId = Constants.DEBUG_ADS ? TEST_ANDROID_REWARDED_AD : ANDROID_REWARDED_AD_2;
        }
        else if (place.Equals(nameof(RewardedAdTypes.ad3)))
        {
            adUnitId = Constants.DEBUG_ADS ? TEST_ANDROID_REWARDED_AD : ANDROID_REWARDED_AD_3;
        }
        else if (place.Equals(nameof(RewardedAdTypes.ad4)))
        {
            adUnitId = Constants.DEBUG_ADS ? TEST_ANDROID_REWARDED_AD : ANDROID_REWARDED_AD_4;
#else
        adUnitId = "unexpected_platform";
#endif
    // create new rewarded ad instance
    RewardedAd rewardedAd = new RewardedAd(adUnitId);
    
    if (place == nameof(RewardedAdTypes.ad1)) {
        // Add Event Handlers
        rewardedAd.OnAdLoaded += HandleRewardedAdLoaded_RewardedAd1;
        rewardedAd.OnAdFailedToLoad += HandleRewardedAdFailedToLoad_RewardedAd1;
        rewardedAd.OnAdOpening += HandleRewardedAdOpening_RewardedAd1;
        rewardedAd.OnAdClosed += HandleRewardedAdClosed_RewardedAd1;
        rewardedAd.OnAdFailedToShow += HandleRewardedAdFailedToShow_RewardedAd1;
        rewardedAd.OnUserEarnedReward += HandleUserEarnedRewardedAd_RewardedAd1;
        
    } else if(place == nameof(RewardedAdTypes.ad2)) {
        // Add Event Handlers
        rewardedAd.OnAdLoaded += HandleRewardedAdLoaded_RewardedAd2;
        rewardedAd.OnAdFailedToLoad += HandleRewardedAdFailedToLoad_RewardedAd2;
        rewardedAd.OnAdOpening += HandleRewardedAdOpening_RewardedAd2;
        rewardedAd.OnAdClosed += HandleRewardedAdClosed_RewardedAd2;
        rewardedAd.OnAdFailedToShow += HandleRewardedAdFailedToShow_RewardedAd2;
        rewardedAd.OnUserEarnedReward += HandleUserEarnedRewardedAd_RewardedAd2;  
    } else if(place == nameof(RewardedAdTypes.ad3)) {
        // Add Event Handlers
        rewardedAd.OnAdLoaded += HandleRewardedAdLoaded_RewardedAd3;
        rewardedAd.OnAdFailedToLoad += HandleRewardedAdFailedToLoad_RewardedAd3;
        rewardedAd.OnAdOpening += HandleRewardedAdOpening_RewardedAd3;
        rewardedAd.OnAdClosed += HandleRewardedAdClosed_RewardedAd3;
        rewardedAd.OnAdFailedToShow += HandleRewardedAdFailedToShow_RewardedAd3;
        rewardedAd.OnUserEarnedReward += HandleUserEarnedRewardedAd_RewardedAd3;  
    }else if(place == nameof(RewardedAdTypes.ad4)) {
        // Add Event Handlers
        rewardedAd.OnAdLoaded += HandleRewardedAdLoaded_RewardedAd4;
        rewardedAd.OnAdFailedToLoad += HandleRewardedAdFailedToLoad_RewardedAd4;
        rewardedAd.OnAdOpening += HandleRewardedAdOpening_RewardedAd4;
        rewardedAd.OnAdClosed += HandleRewardedAdClosed_RewardedAd4;
        rewardedAd.OnAdFailedToShow += HandleRewardedAdFailedToShow_RewardedAd4;
        rewardedAd.OnUserEarnedReward += HandleUserEarnedRewardedAd_RewardedAd4;  
    }

    rewardedAd.LoadAd(CreateAdRequest());
    return rewardedAd;

}

public void HandleRewardedAdClosed_RewardedAd3(object sender, EventArgs args)
    {
        _onClosedAd_ad3?.Invoke();
        if (DetachRewardedAdListeners(nameof(RewardedAdTypes.ad3))) {
            this.RewardedAd3 = RequestAndLoadRewardedAd(nameof(RewardedAdTypes.ad3));
        }
    }

public void HandleUserEarnedRewardedAd_RewardedAd3(object sender, Reward args)
{
    _onAd3_GotReward?.Invoke();
}

我对所有奖励广告都有相同的方法。

当我测试游戏时，我点击了奖励广告（ad3 或 ad4）。 我看到 AdOpening 事件运行。打开广告，然后我看到它火了

HandleUserEarnedRewardedAd_RewardedAd3 event received
    AdManager:HandleUserEarnedRewardedAd_RewardedAd3(Object, Reward)
    

之后我得到一个

E/CRASH: Cause: null pointer dereference

在广告打开和奖励授予标题显示时。关闭广告后，应用程序会立即关闭。

有什么解决办法？ 是否限制在一个应用中使用 4 个激励广告单元？或者我不必在请求新的激励广告之前分离 Ad3 变量？