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Have you ever launched your iOS app only to watch your in-app purchases crash and burn with a mysterious SKErrorDomain Error 4? You’re not alone. This frustrating error blocks transactions, confuses users, and slashes your revenue potential—but it doesn’t have to.
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Unlike generic iOS errors, SKErrorDomain Error 4 strikes specifically at your monetization pipeline. In this manual, I’ll explain exactly what causes this “clientInvalid” error and walk you through proven solutions that work in 2026. You’ll get concrete code examples, step-by-step troubleshooting, and prevention strategies that fix the problem for good.
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Let’s transform this revenue-blocking headache into a minor speed bump.
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wp:image {“id”:48137,”linkDestination”:”custom”,”align”:”center”}
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What is SKErrorDomain Error 4? Understanding the “clientInvalid” Error
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SKErrorDomain Error 4 (officially labeled as “clientInvalid”) occurs when iOS’s StoreKit framework determines that the client attempting to make a purchase isn’t authorized to complete the transaction. This error belongs to Apple’s StoreKit error domain, which handles all in-app purchase operations in iOS applications.
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When this error triggers, your app receives an error object that looks something like this:
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Error Domain=SKErrorDomain Code=4
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“Client is not authorized to make purchases”
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UserInfo={NSLocalizedDescription=Client is not authorized to make purchases}
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The key detail is error code 4, which indicates client-side authorization problems rather than server issues or product configuration errors. This distinction matters because it narrows down where to focus your troubleshooting.
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In practical terms, this means something about the user’s device setup, Apple ID configuration, or purchase restrictions preventing the transaction from proceeding. The issue could stem from parental controls, payment method problems, or specific account limitations requiring different handling strategies.
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wp:image {“id”:48133,”linkDestination”:”custom”,”align”:”center”}
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What Triggers SKErrorDomain Error 4? Root Causes Explained
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Understanding what causes SKErrorDomain Error 4 helps you implement targeted solutions rather than generic fixes. Here are the most common triggers:
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1. Parental Controls & Restrictions
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The most frequent cause involves device restrictions that explicitly block in-app purchases. These settings override your app’s purchase requests, immediately triggering the error.
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Problematic Scenario:
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// This standard purchase request will fail with Error 4 if restrictions are enabled
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let payment = SKPayment(product: product)
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SKPaymentQueue.default().add(payment)
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Prevention Solution:
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// Check for purchase capability before attempting transaction
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if SKPaymentQueue.canMakePayments() {
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let payment = SKPayment(product: product)
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SKPaymentQueue.default().add(payment)
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} else {
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// Inform user about purchase restrictions
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showRestrictionsAlert()
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}
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2. Invalid Payment Methods
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When a user’s payment method is declined, expired, or doesn’t match their App Store region, SKErrorDomain Error 4 occurs. This is particularly common with temporary cards or accounts with regional mismatches.
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Common Problem Pattern:
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// Directly attempting purchase without validation
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func buyProduct(_ product: SKProduct) {
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let payment = SKPayment(product: product)
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SKPaymentQueue.default().add(payment)
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}
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Improved Implementation:
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func buyProduct(_ product: SKProduct) {
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// First verify the user is logged in and can make purchases
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guard SKPaymentQueue.canMakePayments() else {
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showAuthorizationError()
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return
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}
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// Add proper error handling in your transaction observer
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let payment = SKPayment(product: product)
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SKPaymentQueue.default().add(payment)
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}
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// In your SKPaymentTransactionObserver
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func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
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for transaction in transactions {
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switch transaction.transactionState {
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case .failed:
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if let error = transaction.error as? SKError, error.code == .clientInvalid {
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// Guide user to check payment method
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showPaymentMethodAlert()
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}
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queue.finishTransaction(transaction)
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// Handle other states…
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}
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}
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}
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3. App Store Sign-In Issues
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A surprisingly common cause is users not being signed adequately into their App Store accounts or using different accounts for the app and store.
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Detection Code:
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// Adding a specific check for App Store login status
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func verifyStoreAccountStatus(completion: @escaping (Bool) -> Void) {
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if #available(iOS 13.0, *) {
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SKPaymentQueue.default().presentCodeRedemptionSheet()
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// If this doesn’t throw an error, user is signed in
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completion(true)
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} else {
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// For older iOS versions, we can only check general payment capability
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completion(SKPaymentQueue.canMakePayments())
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}
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}
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4. Sandbox Testing Environment Limitations
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SKErrorDomain Error 4 frequently appears during development due to sandbox testing constraints and misconfigured test accounts.
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Common Development Issue:
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// Testing without proper sandbox account setup
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func testPurchase() {
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// This will fail with Error 4 if sandbox account isn’t properly configured
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let payment = SKPayment(product: testProduct)
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SKPaymentQueue.default().add(payment)
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}
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Solution:
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// Proper sandbox testing approach
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func testPurchase() {
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// First verify we’re in sandbox environment
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if let receiptURL = Bundle.main.appStoreReceiptURL,
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receiptURL.lastPathComponent == “sandboxReceipt” {
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print(“Running in sandbox environment – ensure test account is properly configured”)
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}
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// Then proceed with proper error handling
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if SKPaymentQueue.canMakePayments() {
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let payment = SKPayment(product: testProduct)
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SKPaymentQueue.default().add(payment)
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} else {
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print(“Sandbox test account cannot make payments – check configuration”)
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}
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}
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Prevention vs. Recovery Strategies for SKErrorDomain Error 4
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| Prevention Techniques | Recovery Strategies |
| Always check SKPaymentQueue.canMakePayments() before attempting purchases | Present clear error messaging guiding users to check restrictions |
| Implement receipt validation to verify the purchase environment | Provide direct App Store settings links to fix payment methods |
| Use StoreKit Testing in Xcode to simulate various error conditions | Cache failed purchase requests for retry after authorization is fixed |
| Monitor transaction observer errors proactively | Implement graceful fallbacks when purchases fail |
| Verify product identifiers before purchase attempts | Guide users through account verification steps |
| Test across multiple Apple ID types (restricted, full access) | Offer alternative payment restoration flows |
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wp:image {“id”:48134,”linkDestination”:”custom”,”align”:”center”}
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Diagnosing SKErrorDomain Error 4: Step-by-Step Troubleshooting
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When SKErrorDomain Error 4 appears, follow this systematic approach to identify the exact cause:
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1. Enable Enhanced StoreKit Logging
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Start by implementing detailed StoreKit logging to capture the full context of the error:
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// Enable enhanced StoreKit logging
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func enableDetailedStoreKitLogging() {
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if #available(iOS 14.0, *) {
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// Use the newer unified logging system
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os_log(“StoreKit Transaction Beginning”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “storekit”), type: .debug)
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} else {
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// Fallback for older iOS versions
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print(“[StoreKit] Transaction Beginning”)
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}
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}
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// Log specific error details
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func logStoreKitError(_ error: Error) {
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if let skError = error as? SKError, skError.code == .clientInvalid {
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let errorCode = skError.code.rawValue
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let errorDescription = skError.localizedDescription
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print(“SKErrorDomain Error: Code \(errorCode) – \(errorDescription)”)
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// Log additional context
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print(“User Account Status: \(SKPaymentQueue.canMakePayments() ? “Can make payments” : “Cannot make payments”)”)
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}
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}
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Real error log example:
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[StoreKit] Transaction Failed: Error Domain=SKErrorDomain Code=4 “Client is not authorized to make purchases” UserInfo={NSLocalizedDescription=Client is not authorized to make purchases}
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User Account Status: Cannot make payments
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2. Create a Test Transaction
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Implement a diagnostic purchase method that captures specific error details:
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func runDiagnosticPurchase(for productID: String, completion: @escaping (SKErrorDomain?) -> Void) {
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// First fetch the product
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let request = SKProductsRequest(productIdentifiers: [productID])
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request.delegate = self
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request.start()
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// In the delegate method:
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// func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
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// if let product = response.products.first {
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// // Attempt purchase with error trapping
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// let payment = SKPayment(product: product)
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// SKPaymentQueue.default().add(payment)
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// }
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// }
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// Then in your transaction observer:
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// if transaction.transactionState == .failed, let error = transaction.error as? SKError {
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// completion(error)
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// }
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}
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3. Check Device Restrictions Status
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Determine if restrictions are enabled with this utility method:
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func checkPurchaseRestrictions(completion: @escaping (Bool, String) -> Void) {
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if SKPaymentQueue.canMakePayments() {
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completion(false, “No purchase restrictions detected”)
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} else {
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completion(true, “Purchase restrictions are active on this device”)
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// Additional diagnostics for iOS 14+
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if #available(iOS 14.0, *) {
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SKPaymentQueue.default().presentCodeRedemptionSheet()
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// This will fail with a specific error if there are account issues
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}
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}
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}
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4. Verify Receipt Environment
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Determine if you’re in production or sandbox to narrow down potential causes:
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swift
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func checkReceiptEnvironment() -> String {
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guard let receiptURL = Bundle.main.appStoreReceiptURL else {
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return “No receipt found”
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}
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if receiptURL.lastPathComponent == “sandboxReceipt” {
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return “Sandbox environment”
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} else {
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return “Production environment”
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}
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}
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wp:image {“id”:48135,”linkDestination”:”custom”,”align”:”center”}
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Implementing Robust SKErrorDomain Error 4 Handling
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Let’s build a comprehensive solution that prevents, detects, and handles SKErrorDomain Error 4 effectively:
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import StoreKit
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import os.log
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class PurchaseManager: NSObject, SKPaymentTransactionObserver {
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// Singleton instance
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static let shared = PurchaseManager()
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// Completion handler typealias
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typealias PurchaseCompletion = (Bool, Error?) -> Void
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// Active purchase completions
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private var purchaseCompletions: [String: PurchaseCompletion] = [:]
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// MARK: – Initialization
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private override init() {
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super.init()
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SKPaymentQueue.default().add(self)
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}
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deinit {
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SKPaymentQueue.default().remove(self)
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}
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// MARK: – Public Methods
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/// Validates if purchases are possible before attempting them
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func canMakePurchases() -> Bool {
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return SKPaymentQueue.canMakePayments()
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}
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/// Comprehensive pre-purchase validation
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func validatePurchaseCapability() -> (canPurchase: Bool, reason: String?) {
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if !SKPaymentQueue.canMakePayments() {
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return (false, “Purchase restrictions are enabled on this device”)
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}
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// Check receipt environment for additional context
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let environment = checkReceiptEnvironment()
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if environment == “Sandbox environment” {
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// Log this for debugging but don’t prevent the purchase
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os_log(“Running in sandbox environment”, type: .debug)
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}
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return (true, nil)
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}
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/// Attempt to purchase a product with proper error handling
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func purchase(productID: String, completion: @escaping PurchaseCompletion) {
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// Validate purchase capability first
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let capability = validatePurchaseCapability()
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guard capability.canPurchase else {
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// Handle SKErrorDomain Error 4 preemptively
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let error = NSError(domain: SKErrorDomain,
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code: SKError.clientInvalid.rawValue,
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userInfo: [NSLocalizedDescriptionKey: capability.reason ?? “Client is not authorized to make purchases”])
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completion(false, error)
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return
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}
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// Fetch the product first
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let productRequest = SKProductsRequest(productIdentifiers: [productID])
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productRequest.delegate = self
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// Store completion handler for later
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purchaseCompletions[productID] = completion
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// Start the request
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productRequest.start()
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}
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// MARK: – Private Methods
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private func checkReceiptEnvironment() -> String {
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guard let receiptURL = Bundle.main.appStoreReceiptURL else {
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return “No receipt found”
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}
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if receiptURL.lastPathComponent == “sandboxReceipt” {
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return “Sandbox environment”
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} else {
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return “Production environment”
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}
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}
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private func handleClientInvalidError(transaction: SKPaymentTransaction, completion: PurchaseCompletion?) {
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let productID = transaction.payment.productIdentifier
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// Log detailed diagnostics
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os_log(“SKErrorDomain Error 4 occurred for product: %{public}@”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “errors”), type: .error, productID)
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// Create a user-friendly error object
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let userInfo: [String: Any] = [
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NSLocalizedDescriptionKey: “Unable to complete purchase”,
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NSLocalizedRecoverySuggestionErrorKey: “Please check your device restrictions and payment method in Settings → [Your Name] → Payment & Shipping.”
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]
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let clientInvalidError = NSError(domain: SKErrorDomain, code: SKError.clientInvalid.rawValue, userInfo: userInfo)
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// Invoke completion handler
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completion?(false, clientInvalidError)
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// Finish the transaction
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SKPaymentQueue.default().finishTransaction(transaction)
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}
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// MARK: – SKPaymentTransactionObserver
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func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
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for transaction in transactions {
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let productID = transaction.payment.productIdentifier
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let completion = purchaseCompletions[productID]
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switch transaction.transactionState {
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case .purchasing:
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os_log(“Transaction in progress for %{public}@”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “transactions”), type: .debug, productID)
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case .purchased, .restored:
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os_log(“Transaction successful for %{public}@”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “transactions”), type: .info, productID)
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completion?(true, nil)
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purchaseCompletions.removeValue(forKey: productID)
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queue.finishTransaction(transaction)
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case .failed:
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os_log(“Transaction failed for %{public}@”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “transactions”), type: .error, productID)
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if let error = transaction.error as? SKError, error.code == .clientInvalid {
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// Handle SKErrorDomain Error 4 specifically
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handleClientInvalidError(transaction: transaction, completion: completion)
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} else {
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// Handle other errors
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completion?(false, transaction.error)
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}
/wp:paragraph
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purchaseCompletions.removeValue(forKey: productID)
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queue.finishTransaction(transaction)
/wp:paragraph
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case .deferred:
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os_log(“Transaction deferred for %{public}@”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “transactions”), type: .info, productID)
/wp:paragraph
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@unknown default:
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os_log(“Unknown transaction state for %{public}@”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “transactions”), type: .error, productID)
/wp:paragraph
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}
/wp:paragraph
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}
/wp:paragraph
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}
/wp:paragraph
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}
/wp:paragraph
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// MARK: – SKProductsRequestDelegate Extension
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extension PurchaseManager: SKProductsRequestDelegate {
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func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
/wp:paragraph
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if response.products.isEmpty {
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for productID in response.invalidProductIdentifiers {
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if let completion = purchaseCompletions[productID] {
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let error = NSError(domain: SKErrorDomain, code: SKError.unknown.rawValue, userInfo: [NSLocalizedDescriptionKey: “Invalid product identifier: \(productID)”])
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completion(false, error)
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purchaseCompletions.removeValue(forKey: productID)
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}
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}
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return
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}
/wp:paragraph
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// Process valid products
/wp:paragraph
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for product in response.products {
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if let completion = purchaseCompletions[product.productIdentifier] {
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// Attempt purchase with the valid product
/wp:paragraph
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let payment = SKPayment(product: product)
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SKPaymentQueue.default().add(payment)
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// Note: Don’t call completion here – wait for transaction observer
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}
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}
/wp:paragraph
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}
/wp:paragraph
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func request(_ request: SKRequest, didFailWithError error: Error) {
/wp:paragraph
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os_log(“Product request failed: %{public}@”, log: OSLog(subsystem: “com.yourapp.purchases”, category: “products”), type: .error, error.localizedDescription)
/wp:paragraph
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// Extract product ID from the request if possible
/wp:paragraph
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if let productRequest = request as? SKProductsRequest,
/wp:paragraph
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let productIDs = productRequest.value(forKey: “productIdentifiers”) as? Set<String>,
/wp:paragraph
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let productID = productIDs.first {
/wp:paragraph
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if let completion = purchaseCompletions[productID] {
/wp:paragraph
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completion(false, error)
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purchaseCompletions.removeValue(forKey: productID)
/wp:paragraph
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}
/wp:paragraph
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}
/wp:paragraph
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}
/wp:paragraph
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}
/wp:paragraph
wp:heading {“level”:3}
Integration in Your View Controller
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Here’s how to use the above manager in your UI:
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import UIKit
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import StoreKit
/wp:paragraph
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class StoreViewController: UIViewController {
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// MARK: – Properties
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let productID = “com.yourapp.premium_subscription”
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// MARK: – UI Elements
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lazy var purchaseButton: UIButton = {
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let button = UIButton(type: .system)
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button.setTitle(“Purchase Premium”, for: .normal)
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button.addTarget(self, action: #selector(purchaseTapped), for: .touchUpInside)
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return button
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}()
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// MARK: – Lifecycle
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override func viewDidLoad() {
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super.viewDidLoad()
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setupUI()
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// Check purchase capability immediately and update UI
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updatePurchaseButtonState()
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}
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// MARK: – UI Setup
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private func setupUI() {
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// Add purchase button to view hierarchy
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view.addSubview(purchaseButton)
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// Set constraints…
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}
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// MARK: – Actions
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@objc private func purchaseTapped() {
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// Show activity indicator
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showLoadingIndicator()
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// Attempt purchase
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PurchaseManager.shared.purchase(productID: productID) { [weak self] success, error in
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// Hide activity indicator
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self?.hideLoadingIndicator()
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if success {
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// Handle successful purchase
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self?.showPurchaseSuccessUI()
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} else if let skError = error as? SKError, skError.code == .clientInvalid {
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// Handle SKErrorDomain Error 4 specifically
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self?.showClientInvalidErrorUI()
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} else {
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// Handle other errors
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self?.showGenericErrorUI(error: error)
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}
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}
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}
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// MARK: – Helper Methods
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private func updatePurchaseButtonState() {
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let capability = PurchaseManager.shared.validatePurchaseCapability()
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purchaseButton.isEnabled = capability.canPurchase
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if !capability.canPurchase {
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// Show a hint about the restriction
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showRestrictionHint(message: capability.reason ?? “Purchases are restricted on this device”)
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}
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}
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private func showClientInvalidErrorUI() {
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let alert = UIAlertController(
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title: “Purchase Not Allowed”,
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message: “Your device settings or Apple ID prevent making purchases. Please check:\n\n1. Restrictions in Settings → Screen Time → Content & Privacy\n2. Your payment method in Settings → [Your Name] → Payment & Shipping”,
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preferredStyle: .alert
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)
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// Add action to open Settings
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alert.addAction(UIAlertAction(title: “Open Settings”, style: .default) { _ in
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if let settingsURL = URL(string: UIApplication.openSettingsURLString) {
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UIApplication.shared.open(settingsURL)
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}
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})
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alert.addAction(UIAlertAction(title: “Cancel”, style: .cancel))
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present(alert, animated: true)
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}
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// Other UI helper methods…
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}
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wp:image {“id”:48136,”linkDestination”:”custom”,”align”:”center”}
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wp:heading
Conclusion
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SKErrorDomain Error 4 signals a client authorization issue that prevents in-app purchases from completing. The most effective solution is pre-emptive validation using SKPaymentQueue.canMakePayments() before attempting transactions, coupled with clear user guidance when restrictions are detected.
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For developers, implement the comprehensive PurchaseManager class from this guide to handle this error gracefully. Always check purchase capability first, then provide specific guidance to help users resolve their authorization issue—parental controls, payment methods, or App Store account problems.
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