a lil bit of refactioring

packages/in_app_purchase/in_app_purchase_storekit/darwin/Classes/InAppPurchasePlugin.swift

@@ -26,6 +26,7 @@ public class InAppPurchasePlugin: NSObject, FlutterPlugin, InAppPurchaseAPI {
   public var registrar: FlutterPluginRegistrar?
   // This property is optional, as it requires self to exist to be initialized.
   public var paymentQueueHandler: FLTPaymentQueueHandlerProtocol?
+
   internal var updateListenerTask: Any?
   internal var transactionListenerAPI: TransactionCallbacks? = nil
 

packages/in_app_purchase/in_app_purchase_storekit/darwin/Classes/StoreKit2/InAppPurchaseStoreKit2.swift

@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 @available(iOS 15.0, macOS 12.0, *)
-extension InAppPurchasePlugin: InAppPurchase2API {
+extension InAppPurchasePlugin: @preconcurrency InAppPurchase2API {
   // MARK: - Pigeon Functions
 
   // Wrapper method around StoreKit2's canMakePayments() method
@@ -37,6 +37,7 @@ extension InAppPurchasePlugin: InAppPurchase2API {
 
   // Gets the appropriate product, then calls purchase on it.
   // https://developer.apple.com/documentation/storekit/product/3791971-purchase
+  @MainActor
   func purchase(
     id: String, options: SK2ProductPurchaseOptionsMessage?,
     completion: @escaping (Result<SK2ProductPurchaseResultMessage, Error>) -> Void
@@ -58,32 +59,34 @@ extension InAppPurchasePlugin: InAppPurchase2API {
         case .success(let verification):
           switch verification {
           case .verified(let transaction):
-            DispatchQueue.main.async {
-              self.transactionListenerAPI?.transactionUpdated(updatedTransactions: transaction)
-            }
+            self.transactionListenerAPI?.transactionUpdated(updatedTransactions: transaction)
             completion(.success(result.convertToPigeon()))
           case .unverified(_, let error):
             completion(.failure(error))
           }
         case .pending:
           completion(
-            .success(.pending))
+            .failure(
+              PigeonError(
+                code: "storekit2_purchase_pending",
+                message: "This transaction is still pending.", details: "")))
         case .userCancelled:
           completion(
             .failure(
               PigeonError(
                 code: "storekit2_purchase_cancelled",
-                message: "this transaction has been cancelled", details: "")))
+                message: "This transaction has been cancelled.", details: "")))
         @unknown default:
-          fatalError()
+          fatalError("An unknown StoreKit PurchaseResult has been encountered.")
         }
       } catch {
         completion(.failure(error))
       }
-
     }
   }
 
+  /// Wrapper method around StoreKit2's transactions() method
+  /// https://developer.apple.com/documentation/storekit/product/3851116-products
   func transactions(
     completion: @escaping (Result<[SK2TransactionMessage], Error>) -> Void
   ) {
@@ -97,26 +100,21 @@ extension InAppPurchasePlugin: InAppPurchase2API {
     }
   }
 
+  /// Wrapper method around StoreKit2's finish() method https://developer.apple.com/documentation/storekit/transaction/3749694-finish
   func finish(id: Int64, completion: @escaping (Result<Void, Error>) -> Void) {
     Task {
       let transaction = try await fetchTransaction(by: UInt64(id))
       if let transaction = transaction {
         await transaction.finish()
       }
-
     }
   }
 
+  /// This Task listens  to Transation.updates as shown here
+  /// https://developer.apple.com/documentation/storekit/transaction/3851206-updates
+  /// This function should be called as soon as the app starts to avoid missing any Transactions done outside of the app. 
   func startListeningToTransactions() throws {
-    self.updateListenerTask = self.listenForTransactions()
-  }
-
-  func stopListeningToTransactions() throws {
-    self.updateListenerTask = nil
-  }
-
-  func listenForTransactions() -> Task<Void, Error> {
-    return Task.detached {
+    self.updateListenerTask = Task {
       for await verificationResult in Transaction.updates {
         switch verificationResult {
         case .verified(let transaction):
@@ -126,25 +124,29 @@ extension InAppPurchasePlugin: InAppPurchase2API {
         }
       }
     }
+  }
 
+  func stopListeningToTransactions() throws {
+    self.updateListenerTask = nil
   }
 
-  func rawTransactions() async -> [Transaction] {
+  /// Helper function that fetches and unwraps all verified transactions
+  private func rawTransactions() async -> [Transaction] {
     var transactions: [Transaction] = []
 
     for await verificationResult in Transaction.all {
       switch verificationResult {
       case .verified(let transaction):
         transactions.append(transaction)
       case .unverified(_, _):
-        // Handle unverified transactions if necessary
         break
       }
     }
     return transactions
   }
 
-  func fetchTransaction(by id: UInt64) async throws -> Transaction? {
+  /// Helper function to fetch specific transaction
+  private func fetchTransaction(by id: UInt64) async throws -> Transaction? {
     for await result in Transaction.all {
       switch result {
       case .verified(let transaction):

packages/in_app_purchase/in_app_purchase_storekit/darwin/Classes/StoreKit2/TransactionCallbacks.swift

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-class TransactionCallbacks: InAppPurchase2CallbackAPI {
-  var callbackAPI: InAppPurchase2CallbackAPI
+final class TransactionCallbacks: InAppPurchase2CallbackAPI {
+  let callbackAPI: InAppPurchase2CallbackAPI
 
   init(binaryMessenger: FlutterBinaryMessenger) {
     callbackAPI = InAppPurchase2CallbackAPI(binaryMessenger: binaryMessenger)

packages/in_app_purchase/in_app_purchase_storekit/lib/src/in_app_purchase_storekit_platform.dart

@@ -31,7 +31,7 @@ class InAppPurchaseStoreKitPlatform extends InAppPurchasePlatform {
   InAppPurchaseStoreKitPlatform();
 
   /// Experimental flag for StoreKit2.
-  static bool _useStoreKit2 = false;
+  static bool _useStoreKit2 = true;
 
   static late SKPaymentQueueWrapper _skPaymentQueueWrapper;
   static late _TransactionObserver _observer;