In App Purchase - detect whether user has already made that purchase - ios

Question

I have the following code to make In-App-Purchases. Everything works fine and the user is able to purchase (non-consumable) on button click.
Currently I call getProducts() and restorePurchases() inside of AppDelegate - when the user has already made a purchase, I assume it will be fetched with restorePurchases() - how can I detect whether a specific product with its ID has already been purchased to f.e. hide that button.
import Foundation
import StoreKit
class IAPService: NSObject {
private override init() {}
static let shared = IAPService()
var products = [SKProduct]()
let paymentQueue = SKPaymentQueue.default()
private var purchasedProductIdentifiers: Set<String> = []
func getProducts() {
let product: Set = ["123456"]
let request = SKProductsRequest(productIdentifiers: product)
request.delegate = self
request.start()
paymentQueue.add(self)
}
func purchase() {
guard let productToPurchase = products.first else { return }
print(productToPurchase)
let payment = SKPayment(product: productToPurchase)
paymentQueue.add(payment)
}
func restorePurchases() {
paymentQueue.restoreCompletedTransactions()
}
}
extension IAPService: SKProductsRequestDelegate {
func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
self.products = response.products
for product in response.products {
print(product.localizedTitle)
}
}
}
extension IAPService: SKPaymentTransactionObserver {
func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
for transaction in transactions {
print(transaction.transactionState.status(), transaction.payment.productIdentifier)
switch transaction.transactionState {
case .purchasing: break
default: queue.finishTransaction(transaction)
}
}
}
}
extension SKPaymentTransactionState {
func status() -> String {
switch self {
case .deferred: return "deferred"
case .failed: return "failed"
case .purchased: return "purchased"
case .purchasing: return "purchasing"
case .restored: return "restored"
}
}
}

Answer 1

You need to check callback of updatedTransactions for the needed productIdentifier and it's state purchased/restored
func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
for transaction in transactions {
if transaction.payment.productIdentifier == "someId" && ( transaction.transactionState == .purchased || transaction.transactionState == .restored ) {
// purchased / resorted
}
}
}
Useful links
https://www.raywenderlich.com/5456-in-app-purchase-tutorial-getting-started
in-app purchase in Swift with a single product