Unityの機能を利用したアプリ内課金の実装

public class IAPManager : IStoreListener
{
    /// <summary>
    /// 商品情報
    /// </summary>
    public class ProductInfo
    {
        public string ID { private set; get; }
        public ProductType Type { private set; get; }

        public ProductInfo(string _id, ProductType _type) => (ID, Type) = (_id, _type);
    }

    private IStoreController m_storeController;
    private IExtensionProvider m_extensionProvider;

    public bool IsInitialized => m_storeController != null && m_extensionProvider != null;

    /// <summary>
    /// 初期化
    /// </summary>
    public void Initialize(ProductInfo[] _products)
    {
        if (!IsInitialized)
        {
            var m_builder = ConfigurationBuilder.Instance(StandardPurchasingModule.Instance());
            foreach (var product in _products)
            {
                m_builder.AddProduct(product.ID, product.Type);
            }
            UnityPurchasing.Initialize(this, m_builder);
        }
    }

    /// <summary>
    /// 初期化 成功
    /// </summary>
    public void OnInitialized(IStoreController _controller, IExtensionProvider _extensions)
    {
        m_storeController = _controller;
        m_extensionProvider = _extensions;
    }

    /// <summary>
    /// 初期化 失敗
    /// </summary>
    public void OnInitializeFailed(InitializationFailureReason _error)
    {
        // 失敗時のエラー処理を実装
    }

    /// <summary>
    /// 購入成功時
    /// </summary>
    public PurchaseProcessingResult ProcessPurchase(PurchaseEventArgs _purchaseEvent)
    {
        // 購入した商品情報は_purchaseEvent.purchasedProductから取得可能
        return PurchaseProcessingResult.Complete;
    }

    /// <summary>
    /// 購入処理 失敗
    /// </summary>
    public void OnPurchaseFailed(Product _product, PurchaseFailureReason _failureReason)
    {
        // 失敗時のエラー処理を実装
    }

    /// <summary>
    /// 商品購入
    /// </summary>
    public void Purchase(string _productId)
    {
        if (IsInitialized)
        {
            m_storeController.InitiatePurchase(_productId);
        }
        else
        {
            // 初期化が完了する前に呼ばれたときのエラー処理を実装
        }
    }
}