iOS App Store Subscription Integration Guide

To enable native App Store subscriptions for your application, you need to modify your iOS project (Xcode) source code.

1. Capabilities & StoreKit

Ensure your App ID has In-App Purchase capability enabled in Apple Developer Portal. In Xcode, add the In-App Purchase capability to your target.

2. Create the Purchase Manager (Swift)

Create a helper class to handle StoreKit 2 interactions and bridge to the WebView.

import StoreKit
import WebKit

class PurchaseManager: NSObject, SKPaymentTransactionObserver {
    static let shared = PurchaseManager()
    weak var webView: WKWebView?
    
    // Map web product IDs to App Store Product IDs
    let productMap: [String: String] = [
        "monthly": "com.jtdrecipe.pro.monthly",
        "6month": "com.jtdrecipe.pro.6month",
        "yearly": "com.jtdrecipe.pro.yearly"
    ]
    
    override init() {
        super.init()
        SKPaymentQueue.default().add(self)
    }
    
    func purchase(webProductId: String) {
        guard let appStoreId = productMap[webProductId] else { return }
        
        if SKPaymentQueue.canMakePayments() {
            let request = SKMutablePayment()
            request.productIdentifier = appStoreId
            SKPaymentQueue.default().add(request)
        }
    }
    
    // Handle Transactions
    func paymentQueue(_ queue: SKPaymentQueue, updatedTransactions transactions: [SKPaymentTransaction]) {
        for transaction in transactions {
            switch transaction.transactionState {
            case .purchased:
                verifyReceipt(transaction: transaction)
                SKPaymentQueue.default().finishTransaction(transaction)
            case .failed:
                SKPaymentQueue.default().finishTransaction(transaction)
                // Notify web of failure if needed
            case .restored:
                verifyReceipt(transaction: transaction)
                SKPaymentQueue.default().finishTransaction(transaction)
            default: break
            }
        }
    }
    
    func verifyReceipt(transaction: SKPaymentTransaction) {
        guard let appStoreReceiptURL = Bundle.main.appStoreReceiptURL,
              let receiptData = try? Data(contentsOf: appStoreReceiptURL) else { return }
        
        let receiptString = receiptData.base64EncodedString(options: [])
        
        // Send to your backend function
        verifyOnBackend(receipt: receiptString)
    }
    
    func verifyOnBackend(receipt: String) {
        // Construct JSON payload
        let json: [String: Any] = ["receiptData": receipt]
        guard let jsonData = try? JSONSerialization.data(withJSONObject: json) else { return }
        
        // Your backend endpoint
        let url = URL(string: "https://YOUR-APP.base44.app/functions/verifyAppStorePurchase")!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.httpBody = jsonData
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        // Note: You need to handle auth token injection if your function requires "user" context from Base44
        // Or you can pass userId in body and handle it with service role in backend (less secure but easier for wrappers)
        
        let task = URLSession.shared.dataTask(with: request) { data, response, error in
            guard let data = data, error == nil else { return }
            
            // On success, notify WebView
            DispatchQueue.main.async {
                self.webView?.evaluateJavaScript("if(window.onPurchaseSuccess) window.onPurchaseSuccess();", completionHandler: nil)
            }
        }
        task.resume()
    }
}

3. Inject JavaScript Bridge

In your ViewController where you setup the WKWebView, add the script message handler.

import WebKit

class ViewController: UIViewController, WKScriptMessageHandler {
    var webView: WKWebView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let contentController = WKUserContentController()
        // Register the handler name 'purchaseSubscription'
        contentController.add(self, name: "purchaseSubscription")
        
        let config = WKWebViewConfiguration()
        config.userContentController = contentController
        
        webView = WKWebView(frame: view.bounds, configuration: config)
        PurchaseManager.shared.webView = webView
        // ... load your URL ...
    }
    
    // Handle calls from JavaScript
    func userContentController(_ userContentController: WKUserContentController, didReceive message: WKScriptMessage) {
        if message.name == "purchaseSubscription",
           let body = message.body as? [String: Any],
           let productId = body["productId"] as? String {
            
            // Trigger purchase
            PurchaseManager.shared.purchase(webProductId: productId)
        }
    }
}

4. Backend Configuration

Don't forget to set the APPLE_SHARED_SECRET in your Base44 App Secrets. You can get this from App Store Connect under the "Users and Access" or App-specific Shared Secret section.