feat: add Objective-C/KMP support with @objc completion handler wrappers

- Add OpenIapModule+ObjC.swift extension
- Provide completion handler versions of all main async methods
- Enable Kotlin Multiplatform interoperability via CocoaPods/cinterop
- All @objc methods use [Any] for non-@objc compatible types

This allows kmp-iap and other Kotlin Multiplatform projects to use OpenIAP
without requiring direct Swift interop.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: hyochan

Sources/OpenIapModule+ObjC.swift

@@ -0,0 +1,245 @@
+import Foundation
+import StoreKit
+
+// MARK: - Objective-C Bridge for Kotlin Multiplatform
+
+@available(iOS 15.0, macOS 14.0, *)
+@objc public extension OpenIapModule {
+
+    // MARK: - Connection Management
+
+    @objc func initConnectionWithCompletion(_ completion: @escaping (Bool, Error?) -> Void) {
+        Task {
+            do {
+                let result = try await initConnection()
+                completion(result, nil)
+            } catch {
+                completion(false, error)
+            }
+        }
+    }
+
+    @objc func endConnectionWithCompletion(_ completion: @escaping (Bool, Error?) -> Void) {
+        Task {
+            do {
+                let result = try await endConnection()
+                completion(result, nil)
+            } catch {
+                completion(false, error)
+            }
+        }
+    }
+
+    // MARK: - Product Management
+
+    @objc func fetchProductsWithSkus(
+        _ skus: [String],
+        type: String?,
+        completion: @escaping ([Any]?, Error?) -> Void
+    ) {
+        Task {
+            do {
+                let productType = type.flatMap { ProductQueryType(rawValue: $0) }
+                let request = ProductRequest(skus: skus, type: productType)
+                let result = try await fetchProducts(request)
+
+                switch result {
+                case .products(let products):
+                    completion(products, nil)
+                case .subscriptions(let subscriptions):
+                    completion(subscriptions, nil)
+                }
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    @objc func getPromotedProductIOSWithCompletion(_ completion: @escaping (Any?, Error?) -> Void) {
+        Task {
+            do {
+                let product = try await getPromotedProductIOS()
+                completion(product as Any?, nil)
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    // MARK: - Purchase Management
+
+    @objc func requestPurchaseWithSku(
+        _ sku: String,
+        quantity: Int,
+        type: String?,
+        completion: @escaping (Any?, Error?) -> Void
+    ) {
+        Task {
+            do {
+                let productType = type.flatMap { ProductQueryType(rawValue: $0) } ?? .inApp
+                let iosProps = RequestPurchaseIosProps(
+                    andDangerouslyFinishTransactionAutomatically: nil,
+                    appAccountToken: nil,
+                    quantity: quantity,
+                    sku: sku,
+                    withOffer: nil
+                )
+                let props = RequestPurchaseProps(
+                    request: .purchase(
+                        RequestPurchasePropsByPlatforms(android: nil, ios: iosProps)
+                    ),
+                    type: productType
+                )
+
+                let result = try await requestPurchase(props)
+
+                switch result {
+                case .purchase(let purchase):
+                    completion(purchase as Any, nil)
+                case .purchases(let purchases):
+                    completion(purchases?.first as Any, nil)
+                case .none:
+                    completion(nil, nil)
+                }
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    @objc func restorePurchasesWithCompletion(_ completion: @escaping (Error?) -> Void) {
+        Task {
+            do {
+                try await restorePurchases()
+                completion(nil)
+            } catch {
+                completion(error)
+            }
+        }
+    }
+
+    @objc func getAvailablePurchasesWithCompletion(_ completion: @escaping ([Any]?, Error?) -> Void) {
+        Task {
+            do {
+                let purchases = try await getAvailablePurchases(nil)
+                completion(purchases as [Any], nil)
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    // MARK: - Transaction Management
+
+    @objc func finishTransactionWithPurchaseId(
+        _ purchaseId: String,
+        productId: String,
+        isConsumable: Bool,
+        completion: @escaping (Error?) -> Void
+    ) {
+        Task {
+            do {
+                let purchaseInput = PurchaseInput(
+                    id: purchaseId,
+                    ids: nil,
+                    isAutoRenewing: false,
+                    platform: .ios,
+                    productId: productId,
+                    purchaseState: .purchased,
+                    purchaseToken: nil,
+                    quantity: 1,
+                    transactionDate: Date().timeIntervalSince1970
+                )
+                try await finishTransaction(purchase: purchaseInput, isConsumable: isConsumable)
+                completion(nil)
+            } catch {
+                completion(error)
+            }
+        }
+    }
+
+    @objc func getPendingTransactionsIOSWithCompletion(_ completion: @escaping ([Any]?, Error?) -> Void) {
+        Task {
+            do {
+                let transactions = try await getPendingTransactionsIOS()
+                completion(transactions as [Any], nil)
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    @objc func clearTransactionIOSWithCompletion(_ completion: @escaping (Bool, Error?) -> Void) {
+        Task {
+            do {
+                let result = try await clearTransactionIOS()
+                completion(result, nil)
+            } catch {
+                completion(false, error)
+            }
+        }
+    }
+
+    // MARK: - Validation
+
+    @objc func getReceiptDataIOSWithCompletion(_ completion: @escaping (String?, Error?) -> Void) {
+        Task {
+            do {
+                let receipt = try await getReceiptDataIOS()
+                completion(receipt, nil)
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    // MARK: - Store Information
+
+    @objc func getStorefrontIOSWithCompletion(_ completion: @escaping (String?, Error?) -> Void) {
+        Task {
+            do {
+                let storefront = try await getStorefrontIOS()
+                completion(storefront, nil)
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    // MARK: - Subscription Management
+
+    @objc func getActiveSubscriptionsWithCompletion(_ completion: @escaping ([Any]?, Error?) -> Void) {
+        Task {
+            do {
+                let subscriptions = try await getActiveSubscriptions(nil)
+                completion(subscriptions as [Any], nil)
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+
+    // MARK: - UI
+
+    @objc func presentCodeRedemptionSheetIOSWithCompletion(_ completion: @escaping (Bool, Error?) -> Void) {
+        Task {
+            do {
+                let result = try await presentCodeRedemptionSheetIOS()
+                completion(result, nil)
+            } catch {
+                completion(false, error)
+            }
+        }
+    }
+
+    @objc func showManageSubscriptionsIOSWithCompletion(_ completion: @escaping ([Any]?, Error?) -> Void) {
+        Task {
+            do {
+                let purchases = try await showManageSubscriptionsIOS()
+                completion(purchases as [Any], nil)
+            } catch {
+                completion(nil, error)
+            }
+        }
+    }
+}