IAPViewController.swift

extension ViewController {

    private func initIAP() {

        NotificationCenter.default.addObserver(self, selector: #selector(handleIAPPurchase(_:)), name: .IAPHelperPurchaseNotification, object: nil)

        // IAP 불러오기
        InAppProducts.store.requestProducts { [weak self] (success, products) in
            guard let self = self, success else { return }
            
            // ...
        }
    }

    // 인앱 결제 버튼 눌렀을 때
    private func touchIAP() {
        if let product = products.first {
            InAppProducts.store.buyProduct(product) // 구매하기
        }
    }

    // 결제 후 Notification을 받아 처리
    @objc func handleIAPPurchase(_ notification: Notification) {
        guard let success = notification.object as? Bool else { return }
        
        if success {
            DispatchQueue.main.async {
                let vc = UIAlertController(title: "알림", message: "구매 성공.", preferredStyle: .alert)
                let ok = UIAlertAction(title: "확인", style: .default) { _ in

                    if let mainURL = URL(string: homeurl) {
                        let request = URLRequest(url: mainURL)
                        self.mainWebview.load(request)
                    }
                }
                vc.addAction(ok)
                self.present(vc, animated: true, completion: nil)
            }

        } else {

            DispatchQueue.main.async {
                let vc = UIAlertController(title: "알림", message: "구매에 실패했습니다.", preferredStyle: .alert)
                let ok = UIAlertAction(title: "확인", style: .default, handler: nil)
                vc.addAction(ok)
                self.present(vc, animated: true, completion: nil)
            }
        }
    }
}