Meet StoreKit 2

Session sample code

StoreKit 2

• brand new set of modern and flexible Swift APIs for working with In-App Purchase across iOS, macOS, tvOS, and watchOS

• updates to the in-app purchase transactions, to make it easier to manage

Five main areas:

• Products

• Purchases

• Transaction info

• Transaction history

• Subscription status

Products & Purchases

• New Product struct

  • contains additional data, such as the product type (Product.ProductType) and extended subscription information (Product.SubscriptionInfo)

  • future-compatible with new features via BackingValue, which allows you to retrieve data contained in the product even on SDKs and devices running operating systems that have older versions of StoreKit 2

  • uses async/await for requests and purchases

• purchase is a Product instance method, purchase(options:)

  • the options parameter lets you specify things like quantity, promotional offer, app account token (New)

  • the App account token is a way for you to keep track of which of your app’s user accounts began and completed a transaction.

    • it’s an opaque token (UUID format)

    • created by you

    • linked to the user in-app account

    • stored in transaction forever

Transaction info

• individually signed object for every transaction

• in-app purchase transaction info will now be provided in JSON Web signature

• StoreKit 2 does transaction verification for you, but you can also add your verification on top

Transaction history

• new set of APIs for querying completed transactions in the user’s transaction history

• you can access all of the user’s past transactions with a single API call

• you can also access the latest transaction for a product

• get what products the user has paid for access via currentEntitlements

  • contains all of the non-consumables in the user’s transaction history

  • contains all of the subscription transactions that are currently active

  • any transactions that have been revoked are not included

  • no consumable transactions

• all transactions are available immediately upon app download

• transactions automatically update on every device

• real-time updates

• thanks to transaction history, users no longer need to restore completed transactions when your app is reinstalled

• you still need to provide a UI to restore purchases

• all new StoreKit 2 transactions are available to the old StoreKit API

• all old StoreKit transactions are available to the new StoreKit 2 API

Subscription status

A subscription status has three parts:

1. latest transaction

• give you access to the last transaction that occurred for this subscription

1. renewal state

• enumeration that tells you the current state of the subscription

• base you app logic off this renewal state

1. renewal info

• contains all details about a user’s subscription (e.g. whether auto-renew is on/off, product id of the renewal, expiration reason)

• signed using JWS

• StoreKit 2 will automatically validate the renewal info for you

Signature validation

More details in RFC7515

JSON Web Signature is comprised of three parts:

1. header

• contains metadata about the object, such as which algorithm is used for signing and where to find the certificate used to validate the signature.

• StoreKit 2 currently uses an ECDSA algorithm (supported natively in CryptoKit)

• For the certificate, StoreKit 2 uses the x5c header

• the entire certificate chain is included in the JWS data, no internet connection

1. payload

• main transaction information such as transaction ID, product ID, purchase date

1. signature

• generated using both the header and the payload

Demo

The session has two demos touching all the flows:

• the first demo focuses on getting products, purchasing, and listening to transitions.

• the second demo focuses on transaction history and subscription statuses

• the final code can be found here