AppDelegate.swift

import Purchases

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?

    func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        Purchases.configure(withAPIKey: "<your_api_key>")
        Purchases.shared.delegate = self // set up the delegate

        return true
    }
}

extension AppDelegate : PurchasesDelegate {
    func purchases(_ purchases: Purchases, didReceiveUpdated purchaserInfo: Purchases.PurchaserInfo) {
        
        // Broadcast a notification when the PurchaserInfo changes
        NotificationCenter.default.post(name: NSNotification.Name("kPurchaserInfoUpdated"), object: nil)
    }
}