Swift In App Purchase Non Consumable - ios

Question

I am developing IAP functionality of non consumable (removing Ads).
I've created an helper for all the operation and everything works fine.
When a user buy/restore the purchase i set this:
let save = UserDefaults.standard
save.set(true, forKey: "Purchase")
save.synchronize()
This works fine as long as the user never delete the app.
I was wondering...
Is there a way to know if the user (after deleting and reinstalling the app) already had made a purchase? so to change the title of the button from "purchase" to "restore"?

Answer 1

For every app, Apple requires that you include a "Restore Purchases" button. This is exactly for the problem you are facing. It will recreate the SKPaymentTransaction for every previously purchased IAP with a "restored" state for the iCloud account that is currently signed in at the App Store, and put on the SKPaymentQueue. Read more...

Answer 2

Maybe it would make sense to have a receipt validation in your code, when the user is interacting in your app. (Apple docs: https://developer.apple.com/library/content/releasenotes/General/ValidateAppStoreReceipt/Introduction.html)
Just have a look at this small example:
Init your product requests:
if SKPaymentQueue.canMakePayments() {
print("starting IAPS")
let productIdentifiers = Set(["YOUR_IAPP_IDENTIFIER#1", "YOUR_IAPP_IDENTIFIER#1"])
let request = SKProductsRequest(productIdentifiers: productIdentifiers as Set<String>)
request.delegate = self
request.start()
} else {
print("please enable IAPS")
}
Set your products in your app and do the receipt validation
func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
print("product request")
let myProduct = response.products
for product in myProduct {
if product.productIdentifier == "YOUR_IAPP_IDENTIFIER#1" {
self.productYear = product
} else if product.productIdentifier == "YOUR_IAPP_IDENTIFIER#2" {
self.productMonth = product
}
print("product added")
print(product.productIdentifier)
print(product.localizedTitle)
print(product.localizedDescription)
print(product.price)
self.receiptValidation()
}
Validation example
func receiptValidation() {
self.logger.log.debug("In receipt validation")
if let appStoreReceiptURL = Bundle.main.appStoreReceiptURL,
FileManager.default.fileExists(atPath: appStoreReceiptURL.path) {
do {
let receiptData = try Data(contentsOf: appStoreReceiptURL, options: .alwaysMapped)
let receiptString = receiptData.base64EncodedString(options: [])
let dict = ["receipt-data" : receiptString, "password" : "YOUR_PASSWORD"] as [String : Any]
// Getting the receipt data from the JSON file and other logic
// ...
// ...
}
}
}
Please let me know, if you need more clarification on this. Furthermore you can simply restore it with the PaymentQueue (Apple Doc: https://developer.apple.com/documentation/storekit/skpaymentqueue)

Answer 3

If you provide a login system you will know easily , otherwise
no other way you should put buy and restore buttons for payment Or you store this key-value in
device key-chain and read them in first setup ,but you should know from ios 10.3 If you deleted the app the associated key-chain items will be deleted
Note: Apple states that all apps that have IAP should put a restore payment functionality so, If there is a workaround app will be rejected by Apple