How to make purchase using storekit 2

To make a purchase using StoreKit 2, you can utilize the Swift async/await pattern to perform tasks such as fetching product metadata, purchasing, and retrieving your customer transaction history. Here is a brief overview of the steps involved:

1. Fetch Product Metadata: Use the Product.products(for:) method to fetch the product metadata for the items you want to offer in your app.

2. Initiate a Purchase: Use the Product.purchase() method to initiate a purchase. This method will handle the purchase flow and return a Transaction object upon completion.

3. Handle Transactions: Use the Transaction.updates property to listen for transaction updates and handle them accordingly.

Here is a simple example in Swift:

import StoreKit

func fetchProducts() async throws -> [Product] {
    let productIDs = ["com.example.app.product1", "com.example.app.product2"]
    let products = try await Product.products(for: productIDs)
    return products
}

func purchaseProduct(_ product: Product) async throws -> Transaction {
    let result = try await product.purchase()
    switch result {
    case .success(let verification):
        let transaction = try verification.payloadValue
        // Handle successful purchase
        return transaction
    case .userCancelled, .pending:
        // Handle user cancellation or pending state
        throw PurchaseError.userCancelled
    @unknown default:
        // Handle unknown cases
        throw PurchaseError.unknown
    }
}

func listenForTransactions() {
    Task {
        for await result in Transaction.updates {
            switch result {
            case .verified(let transaction):
                // Handle verified transaction
                await transaction.finish()
            case .unverified(_, _):
                // Handle unverified transaction
            }
        }
    }
}

For more detailed information, you can refer to the session What’s new in StoreKit and In-App Purchase from WWDC 2024. This session covers the new features in StoreKit 2 and provides a comprehensive guide on how to implement in-app purchases using the new APIs.