What are architecture patterns for StoreKit 2 in Swift?

StoreKit 2 offers a robust framework for managing in-app purchases and subscriptions in your iOS applications. Implementing well-structured architecture patterns can help enhance the maintainability and scalability of your app. Here are a few common architecture patterns that can be used when working with StoreKit 2 in Swift:

1. MVC (Model-View-Controller): This is a traditional approach where the model represents the data (Product, Purchase), the view displays the UI (Views, ViewControllers), and the controller handles user interactions.
2. MVP (Model-View-Presenter): This separates the presentation logic from the UI components, making unit testing easier. The presenter handles the interaction with StoreKit 2 and updates the view accordingly.
3. MVC (Model-View-ViewModel): This pattern helps in binding the UI directly to the data model through view models, making it easier to manage the state of your StoreKit purchases and subscriptions.
4. Clean Architecture: This pattern emphasizes separating concerns into layers, which enhances testability and scalability. The data layer can manage StoreKit interactions while the presentation layer deals with UI updates.

Example: Using MVVM with StoreKit 2

import StoreKit

class PurchaseViewModel {
    private var products: [Product] = []
    
    func fetchProducts() async {
        do {
            products = try await Product.products(for: ["com.example.app.product1", "com.example.app.product2"])
        } catch {
            print("Error fetching products: \(error)")
        }
    }
    
    func purchase(product: Product) async {
        do {
            let result = try await AppStore.purchase(product)
            // Handle the purchase result
        } catch {
            print("Purchase failed: \(error)")
        }
    }
}

class PurchaseViewController: UIViewController {
    private var viewModel = PurchaseViewModel()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        Task {
            await viewModel.fetchProducts()
            // Update UI with products
        }
    }
}