如何检查购买的物品

Question

我是SWIFT和编程的初学者。我正在创建一些应用游戏。我在我的应用程序中添加了一些IAP。它的工作非常完美。我有一个非消耗品购买。我需要你的帮助。如何查看购买的商品？当我按下恢复按钮时，我的应用程序恢复我的IAP并显示一切正常。但如果用户没有买东西 - 没有任何反应。但我想告诉用户他们没有买任何东西。

这是我的代码

class MainMenuScene: SKScene, AVAudioPlayerDelegate, SKPaymentTransactionObserver, SKProductsRequestDelegate

 var request:SKProductsRequest = SKProductsRequest()

if(SKPaymentQueue.canMakePayments())
        {print("OK!")}else{print("please enable IAPS")}
let productID:NSSet = NSSet(objects:
        "IAP ID1",
        "IAP ID2",
        "IAP ID3")
    request = SKProductsRequest(productIdentifiers: productID as Set<NSObject> as Set<NSObject> as! Set<String>)
    request.delegate = self
    request.start()

var list = [SKProduct]()
    var p = SKProduct()

    func buyProduct()
    {
        print("buy " + p.productIdentifier)
        let pay = SKPayment(product: p)
        SKPaymentQueue.default().add(self)
        SKPaymentQueue.default().add(pay as SKPayment)
    }

    func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse)
    {
        print("product request")
        let myProduct = response.products

        for product in myProduct {
            print("product added")
            print(product.productIdentifier)
            print(product.localizedTitle)
            print(product.localizedDescription)
            print(product.price)

            list.append(product as SKProduct)
        }
    }

    func paymentQueueRestoreCompletedTransactionsFinished(_ queue: SKPaymentQueue)
    {
        for transaction in queue.transactions
        {
            let t: SKPaymentTransaction = transaction
            let prodID = t.payment.productIdentifier as String

            switch prodID
            {
            case "IAP ID1": add1000Coins()
            case "IAP ID2": add5000Coins()
            case "IAP ID3": unlockAfterPurchase()

            default:
                print("complete")
            }
        }
    }

    func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction])
    {
        for transaction:AnyObject in transactions
        {
            let trans = transaction as! SKPaymentTransaction
            print(trans.error)

                switch trans.transactionState
                {
                case .purchased:
                    print(p.productIdentifier)

            let prodID = p.productIdentifier as String
                switch prodID
                {
                    case "IAP ID1": add1000Coins()
                    case "IAP ID2": add5000Coins()
                    case "IAP ID3": unlockAfterPurchase()

                    default:
                        print("IAP no found")
                }
                    queue.finishTransaction(trans)
                    case .failed:
                        print("buy error")
                        queue.finishTransaction(trans)
                        break
                case .restored:
                    let alert = UIAlertView(title: "Thank You", message: "Your purchase(s) were restored.", delegate: nil, cancelButtonTitle: "OK")
                    alert.show()
                    break
                        default: print("default")
                        break
                }
        }
    }

func finishTransaction(trans:SKPaymentTransaction)
    {

    }

private func paymentQueue(queue: SKPaymentQueue!, removedTransactions transactions: [AnyObject]!)
{

}

func add1000Coins()
{
    //...
}

func add5000Coins()
{
    //...
}

func transactionObserver()
{
    SKPaymentQueue.default().remove(self)
}

func restorePreviousPurchases()
{
    //...
}

func unlockAfterPurchase()
{
    //...
} 

我正在看一些教程，但我不明白如何解决我的问题

请帮我解决代码

P.S。对不起我的英文，感谢您的关注。