オープンソースのSDKで、Androidの
アプリ内購入を統合します。

import StoreKit
class Store: ObservableObject {
    private var productIDs = ["stone"]
    @Published var products = [Product]()
    init() {
        Task {
            await requestProducts()
        }
    }  
    @MainActor
    func requestProducts() async {
        do {
            products = try await Product.products(for: productIDs)
        } catch {
            print(error)
    }
  }
}
Section(header: Text("To buy")) {
 }
ForEach(store.products, id: .id) {
  product in
    HStack {
      Text(product.displayName)
      Spacer()
      Button("(product.displayPrice)") {
    }
  }
}
@Published var purchasedNonConsumables = [Product]()
@MainActor
func purchase(_ product: Product) async throws -> Transaction ? {
  let result =
    try await product.purchase()
  switch result {
    case .success(.verified(let transaction)):
      purchasedNonConsumables.append(product)
      await transaction.finish()
      return transaction
    default:
      return nil
  }
}
Button("(product.displayPrice)") {
 Task {
  try await store.purchase(product)
  }
}
ProductView(
 icon: "❀",
 quantity: "(store.purchasedNonConsumables.count)"
 )
 func listenForTransactions() -> Task < Void, Error > {
  return Task.detached {
    for await result in Transaction.updates {
      switch result {
        case let.verified(transaction):
          guard
          let product = self.products.first(where: {
            $0.id == transaction.productID
          })
          else {
            continue
          }
          self.purchasedNonConsumables.append(product)
          await transaction.finish()
        default:
          continue
      }
    }
  }
}
var transacitonListener: Task<Void, Error>?
init() {
   transacitonListener = listenForTransactions()
   Task {
     await requestProducts()
 }
}
@MainActor
private func handle(transactionVerification result: VerificationResult <Transaction> ) async {
  switch result {
    case let.verified(transaction):
      guard
      let product = self.products.first(where: {
        $0.id == transaction.productID
      })
      else {
        return
      }
      self.purchasedNonConsumables.insert(product)
      await transaction.finish()
    default:
      return
  }
}