Storekit

This walks you through Apple's modern StoreKit 2 APIs for in-app purchases and subscriptions on iOS 16+. It covers the full lifecycle: loading products with Product.products, handling the purchase flow with proper verification, setting up the Transaction.updates listener (which too many people skip), and checking entitlements correctly. The built-in SubscriptionStoreView and StoreView components on iOS 17+ handle most of the UI work for you, which is great if you don't need custom paywall designs. It also shows how to implement offer codes, manage subscription status, and handle edge cases like Family Sharing and Ask to Buy. Use this when you need to actually ship IAP correctly instead of cobbling together examples from outdated tutorials still using SKPaymentQueue.