Adds a payment request to the queue.
- iOS 3.0+
- macOS 10.7+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 6.2+Beta
A payment request.
An application should always have at least one observer of the payment queue before adding payment requests.
The payment request must have a product identifier registered with the Apple App Store and a quantity greater than
0. If either property is invalid,
add throws an exception.
When a payment request is added to the queue, the payment queue processes that request with the Apple App Store and arranges for payment from the user. When that transaction is complete or if a failure occurs, the payment queue sends the
SKPayment object that encapsulates the request to all transaction observers.