In-App Purchase 'Thread 1: Fatal error: Index out of range' - swift

Question

I have no problem when I click on restore purchase. But when I click on unlockProButt or buy100CoinsButt, I get the error "Thread 1: Fatal error: Index out of range". What is the problem? How can I make the purchase smoothly? I have always received errors in all the in-app purchase examples I have tried. I always have problems with this line of code.
Error Line: purchaseMyProduct(validProducts[productIndex])
Error: Thread 1: Fatal error: Index out of range
import UIKit
import StoreKit
class ViewController: UIViewController, SKProductsRequestDelegate, SKPaymentTransactionObserver {
#IBOutlet weak var buy100coinsButton: UIButton!
#IBOutlet weak var unlockProButton: UIButton!
#IBOutlet weak var restorePurchaseButton: UIButton!
var productsRequest = SKProductsRequest()
var validProducts = [SKProduct]()
var productIndex = 0
// viewDidLoad()
override func viewDidLoad() {
super.viewDidLoad()
buy100coinsButton.isHidden = true
unlockProButton.isHidden = true
fetchAvailableProducts()
}
func fetchAvailableProducts() {
let productIdentifiers = NSSet(objects:
"..", // 0
"..." // 1
)
productsRequest = SKProductsRequest(productIdentifiers: productIdentifiers as! Set<String>)
productsRequest.delegate = self
productsRequest.start()
}
func productsRequest (_ request:SKProductsRequest, didReceive response:SKProductsResponse) {
if (response.products.count > 0) {
validProducts = response.products
// 1st IAP Product
let prod100coins = response.products[0] as SKProduct
let prodUnlockPro = response.products[1] as SKProduct
print("1st rpoduct: " + prod100coins.localizedDescription)
print("2nd product: " + prodUnlockPro.localizedDescription)
buy100coinsButton.isHidden = false
unlockProButton.isHidden = false
}
}
func paymentQueue(_ queue: SKPaymentQueue, shouldAddStorePayment payment: SKPayment, for product: SKProduct) -> Bool {
return true
}
func canMakePurchases() -> Bool { return SKPaymentQueue.canMakePayments() }
func purchaseMyProduct(_ product: SKProduct) {
if self.canMakePurchases() {
let payment = SKPayment(product: product)
SKPaymentQueue.default().add(self)
SKPaymentQueue.default().add(payment)
} else { print("Purchases are disabled in your device!") }
}
func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
for transaction:AnyObject in transactions {
if let trans:SKPaymentTransaction = transaction as? SKPaymentTransaction {
switch trans.transactionState {
case .purchased:
SKPaymentQueue.default().finishTransaction(transaction as! SKPaymentTransaction)
if productIndex == 0 {
print("You've bought 100 coins!")
buy100coinsButton.setTitle("Buy another 100 Coins Chest", for: .normal)
} else {
print("You've unlocked the Pro version!")
unlockProButton.isEnabled = false
unlockProButton.setTitle("PRO version purchased", for: .normal)
}
break
case .failed:
SKPaymentQueue.default().finishTransaction(transaction as! SKPaymentTransaction)
print("Payment has failed.")
break
case .restored:
SKPaymentQueue.default().finishTransaction(transaction as! SKPaymentTransaction)
print("Purchase has been successfully restored!")
break
default: break
}}}
}
func restorePurchase() {
SKPaymentQueue.default().add(self as SKPaymentTransactionObserver)
SKPaymentQueue.default().restoreCompletedTransactions()
}
func paymentQueueRestoreCompletedTransactionsFinished(_ queue: SKPaymentQueue) {
print("The Payment was successfull!")
}
// Buttons -------------------------------------
#IBAction func buy100CoinsButt(_ sender: UIButton) {
productIndex = 0
purchaseMyProduct(validProducts[productIndex])
}
#IBAction func unlockProButt(_ sender: UIButton) {
productIndex = 1
purchaseMyProduct(validProducts[productIndex])
}
#IBAction func restorePurchaseButt(_ sender: UIButton) {
restorePurchase()
}
}

Answer 1

you should create a completion handler so you know when your app actually receives the inApp products, so when the delegate "productsRequest" has completed its operation, for this add to your class the appropriate protocol => "SKRequestDelegate" (all these requests are made asynchronously, I hope you know the differences between synchronous and asynchronous, I recommend you to search on google) Now that you have added the SKRequestDelegate protocol dependency to your class, you can implement the two functions that will inform you of the completion or failure of your request: "requestDidFinish" and "request ... didFailWithError", I'll give you an example with some code below, I hope I've been of help to you, for other clarifications please ask :)
extension ViewController : SKRequestDelegate {
// fine della richiesta in app
func requestDidFinish(_ request: SKRequest) {
debugPrint("[IAP] ---- REQUEST COMPLETED ---- ")
}
// Error Request
func request(_ request: SKRequest, didFailWithError error: Error) {
debugPrint("[IAP] Error: ", error)
}
}
Ah I forgot: check that "self.validProducts.count" is greater than 0 otherwise it means that your array is empty and so when you go to => "purchaseMyProduct(validProducts[productIndex])" your application will crash because the "productIndex" position in your "validProducts" array doesn't exist...