Unity In-App Purchases: Implementation Basics & Best Practices

using System.Collections.Generic;
using Unity.Services.Core;
using UnityEngine;
using UnityEngine.Purchasing;
using UnityEngine.Purchasing.Extension;
using UnityEngine.Purchasing.Models;

public class IAPManager : MonoBehaviour
{
    private StoreController _storeController;
    private string _coinProductID = "com.yourgame.coins.100";

    async void Start()
    {
        await UnityServices.InitializeAsync();
        InitializeIAP();
    }

    private void InitializeIAP()
    {
        _storeController = UnityIAPServices.StoreController();
        
        // 1. Subscribe to the v5 events
        _storeController.OnProductsFetched += OnProductsFetched;
        _storeController.OnPurchasesFetched += OnPurchasesFetched;
        _storeController.OnPurchasesFetchFailed += OnPurchasesFetchFailed;
        
        _storeController.OnPurchasePending += OnPurchasePending;
        _storeController.OnPurchaseConfirmed += OnPurchaseConfirmed;
        _storeController.OnPurchaseFailed += OnPurchaseFailed;
        _storeController.OnPurchaseDeferred += OnPurchaseDeferred;
        _storeController.OnStoreDisconnected += OnStoreDisconnected;
        
        // 2. Connect to the store
        _storeController.Connect().ContinueWith(task => {
            if (task.IsCompletedSuccessfully) {
                var products = new List<ProductDefinition> {
                    new ProductDefinition(_coinProductID, ProductType.Consumable)
                };
                // 3. Fetch the product catalog
                _storeController.FetchProducts(products);
            }
        });
    }

    private void OnProductsFetched(List<Product> products)
    {
        Debug.Log("Catalog Products fetched successfully.");
        // 4. Fetch past purchases after the catalog is ready
        _storeController.FetchPurchases();
    }

    private void OnPurchasesFetched(Orders orders)
    {
        Debug.Log("Past purchases fetched. Restoring non-consumables...");
        // Loop through orders.ConfirmedOrders and restore entitlements if necessary
    }

    private void OnPurchasesFetchFailed(PurchasesFetchFailureDescription description)
    {
        Debug.LogError($"Failed to fetch purchases: {description.reason}");
    }

    private void OnPurchasePending(PendingOrder order)
    {
        Debug.Log("Purchase pending! Granting reward...");
        
        // 5. Fulfill the order. Ensure logic is idempotent!
        bool success = GrantReward(order.ProductId, order.TransactionId);
        
        if (success) {
            // 6. Only confirm the purchase AFTER successful fulfillment
            _storeController.ConfirmPurchase(order);
        }
    }

    private void OnPurchaseConfirmed(Order order)
    {
        // Confirmation can fail. Check the actual state rather than assuming success.
        if (order.State == OrderState.Confirmed) {
            Debug.Log("Purchase successfully confirmed with the store.");
        } else {
            Debug.LogWarning($"Confirmation was not successful. State: {order.State}");
        }
    }

    private void OnPurchaseFailed(FailedOrder order)
    {
        Debug.LogWarning($"Purchase failed: {order.FailureReason}");
        // Update UI to inform the user
    }

    private void OnPurchaseDeferred(DeferredOrder order)
    {
        Debug.Log("Purchase deferred (e.g., Ask to Buy on iOS). Waiting for parental approval.");
    }

    private void OnStoreDisconnected(StoreConnectionFailureDescription description)
    {
        Debug.LogWarning($"Store disconnected: {description.reason}");
    }

    public void BuyCoins()
    {
        _storeController.PurchaseProduct(_coinProductID);
    }

    private bool GrantReward(string productId, string transactionId)
    {
        // Check if transactionId was already rewarded, if not, grant it
        return true;
    }
}