In-App Purchases (Obj-C)

PurchaseViewController.m

// Called in viewDidLoad callback. 
- (void)validateProducts
{
    NSString *productId = @"product_id_from_app_store_connect";
    NSSet *productIdentifiers = [NSSet setWithObject:productId];
    
    SKProductsRequest *request = [[SKProductsRequest alloc] initWithProductIdentifiers:productIdentifiers];
    request.delegate = self;
    self.productsRequest = request;
    
    [self.productsRequest start];
}

// Called when user taps "Subscribe" or "Purchase" or whatever.
- (void)subscribeUser
{
    if (![SKPaymentQueue canMakePayments]) {
        [self displayErrorWithTitle:@"Oops" message:@"You aren't allowed to make in-app purchases. Please update your Settings and try again"];
        return;
    }
    if (!self.subscriptionProduct) {
        DDLogError(@"no subscription to purchase");
        [self displayErrorWithTitle:@"We're Sorry" message:@"Something went wrong. Please try again."];
        return;
    }
    
    SKPayment *payment = [SKPayment paymentWithProduct:self.subscriptionProduct];
    [[SKPaymentQueue defaultQueue] addPayment:payment];
}

// Called when user taps a "restore my purchase" button.
- (void)restoreSubscription
{
    [[SKPaymentQueue defaultQueue] restoreCompletedTransactions];
}

#pragma mark - <SKPaymentTransactionObserver>

- (void)paymentQueue:(SKPaymentQueue *)queue updatedTransactions:(NSArray<SKPaymentTransaction *> *)transactions
{
    for (SKPaymentTransaction *transaction in transactions) {
        switch (transaction.transactionState) {
            case SKPaymentTransactionStatePurchased:
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                // Any other custom success handling logic, e.g. pop-up.
                break;
            case SKPaymentTransactionStateRestored:
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                // Restoration logic, pop-up, etc.
                break;
            case SKPaymentTransactionStateFailed:
                [[SKPaymentQueue defaultQueue] finishTransaction:transaction];
                // Show error, etc.
                break;
            default:
                // Probably shouldn't happen, might want to display an error.
                break;
        }
    }
}

#pragma mark - <SKProductsRequestDelegate>

- (void)productsRequest:(SKProductsRequest *)request didReceiveResponse:(SKProductsResponse *)response
{
    // Below assumes one possible product for purchase, modify if you support multiple.
    if (response.products.count != 1) {
        DDLogError(@"Subscription product not valid");
    }
    else {
        self.subscriptionProduct = response.products[0];
    }
    
    [[SKPaymentQueue defaultQueue] addTransactionObserver:self];
    // Any custom logic to display the available products or buttons to purchase.
}