StoreKit

import StoreKit

func loadProducts() async throws -> [Product] {
    let productIDs = [
        "com.example.subscription.monthly",
        "com.example.consumable.coins"
    ]
    
    let products = try await Product.products(for: productIDs)
    return products
}

import StoreKit

func purchase(_ product: Product) async throws -> Transaction? {
    let result = try await product.purchase()
    
    switch result {
    case .success(let verification):
        let transaction = try checkVerified(verification)
        await transaction.finish()
        return transaction
        
    case .userCancelled, .pending:
        return nil
        
    @unknown default:
        return nil
    }
}

func checkVerified<T>(_ result: VerificationResult<T>) throws -> T {
    switch result {
    case .unverified:
        throw StoreError.failedVerification
    case .verified(let safe):
        return safe
    }
}

import StoreKit

func observeTransactionUpdates() -> Task<Void, Never> {
    Task {
        for await result in Transaction.updates {
            do {
                let transaction = try checkVerified(result)
                
                // Deliver content to the user
                await updatePurchasedProducts()
                
                // Finish the transaction
                await transaction.finish()
            } catch {
                print("Transaction verification failed")
            }
        }
    }
}