StoreKit

Use Apple's public Lookup API to check whether a newer App Store version is available, compare it safely, and send users to the App Store from SwiftUI.

Use StoreKit's monthly billing plan for yearly subscriptions, show the commitment honestly, purchase the monthly plan, and track entitlement versus commitment progress.

StoreKit 2 gives us two important transaction sequences: one for reading what the customer owns now and one for listening to changes. Let's build a tiny entitlement store that uses both without accidentally missing purchases.