Cannot get receipt data

Question

I am implementing the discount code feature and we use the following code to show the redeem sheet.

SKPaymentQueue.default().presentCodeRedemptionSheet()

After redemption, I have to show the information about the discount code redemption and I know I can get that information by checking the receipt data. To get the receipt data after applying the discount, I use the following code.

if let url = Bundle.main.appStoreReceiptURL, 
   let data = try? Data(contentsOf: url) {
      let receiptBase64 = data.base64EncodedString()
      print(receiptBase64)
}

Here, data is always nil. What's wrong here? I'm testing this feature on real devices.

The URL is: file:///private/var/mobile/Containers/Data/Application/XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX/StoreKit/sandboxReceipt

Answer 1

The issue was I used the wrong code to finalize the transaction.

Wrong code:

func purchase(_ product: Product) async throws -> StoreKit.Transaction? {
    let result = try await product.purchase()
    switch result {
        case .success(let verification):
            let transaction = try checkVerified(verification)
            await transaction.finish() // I thought when this code runs the receipt data is generated but it doesn't.
            return transaction
        case .userCancelled, .pending:
            return nil
        default:
            return nil
        }
    }
}

func checkVerified<T>(_ result: VerificationResult<T>) throws -> T {
    switch result {
        case .unverified:
            throw StoreError.failedVerification
        case .verified(let safe):
            return safe
        }
    }
}

Fix: SKPaymentQueue.default().finishTransaction(SKPaymentTransaction) should be called.

extension IAPManager: SKPaymentTransactionObserver {
    public func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
        for transaction in transactions {
            switch (transaction.transactionState) {
            case .purchased:
                SKPaymentQueue.default().finishTransaction(transaction) // This is correct.
                break
            case .failed:
                SKPaymentQueue.default().finishTransaction(transaction)
                break
            case .restored:
                SKPaymentQueue.default().finishTransaction(transaction)
                break
            case .deferred, .purchasing:
                break
            default:
                break
            }
        }
    }
}

Now, I see the receipt data!