Example.swift

// Starts products loading and sets transaction observer delegate
    @objc func startWith(arrayOfIds : Set<String>!, sharedSecret : String){
        SKPaymentQueue.default().add(self)
        self.sharedSecret = sharedSecret
        self.productIds = arrayOfIds
        loadProducts()
    }
    
    private func loadProducts(){
        let request = SKProductsRequest.init(productIdentifiers: productIds)
        request.delegate = self
        request.start()
    }
    
    public func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {                
        products = response.products
        DispatchQueue.main.async {
            NotificationCenter.default.post(name: IAP_PRODUCTS_DID_LOAD_NOTIFICATION, object: nil)
        }
    }
    
    func request(_ request: SKRequest, didFailWithError error: Error){
        print("error: \(error.localizedDescription)")
    }