ios - 在 NSObject 类中设置协议(protocol)并在 UIViewController 类中调用它们

Question

我是 swift 新手，我只是想知道是否有一种方法可以在 NSObject 类中声明一些委托(delegate)协议(protocol)并在 UIViewController 类中调用它们。我尝试这样做，但它引发了运行时异常。我在类中的代码如下。

NSObject 类

import UIKit
import StoreKit
class InAppPurchase: NSObject, SKProductsRequestDelegate, SKPaymentTransactionObserver {
var productsList = [SKProduct]()
    var productToPurchase = SKProduct()
    var productID = ""
    let PURCHASE_ID_PREFIX = "com.aux.ApplePaySample."


    public func initPayment (productID: String) {
        self.productID = PURCHASE_ID_PREFIX + productID
        print("Initializing Purchase Product ID: \(self.productID)")
        if SKPaymentQueue.canMakePayments() {
            let productID: NSSet = NSSet(objects: self.productID)
            let request: SKProductsRequest = SKProductsRequest(productIdentifiers: productID as! Set<String>)
            request.delegate = self
            request.start()
        }else {
            print("In App Purchases not enabled")
        }
    }

    func buyProduct() {
        let payment = SKPayment(product: productToPurchase)
        SKPaymentQueue.default().add(self)
        SKPaymentQueue.default().add(payment as SKPayment)
    }


    public func productsRequest(_ request: SKProductsRequest, didReceive response: SKProductsResponse) {
        let myProducts = response.products
        for product in myProducts {
            print("\(product.productIdentifier) \(product.price) \(product.localizedDescription)")
            productsList.append(product)
        }

        for product in productsList {
            let productID = product.productIdentifier
            if productID == self.productID {
                productToPurchase = product
                buyProduct()
            }
        }

    }
}

UIViewController类

import UIKit
import StoreKit

class InAppViewController: UIViewController{
    @IBOutlet var buyButton: UIButton!
    // SKProductsRequestDelegate, SKPaymentTransactionObserver 
    let defaults = UserDefaults.standard
    var product_id: NSString?
    override func viewDidLoad() {
        super.viewDidLoad()

    InAppPurchase().initPayment(productID: "101")
}

从技术上讲，我的 initPayment 方法应该触发委托(delegate)，但它没有发生，而且我没有得到我在这里缺少的东西。非常感谢您的帮助。

Answer 1

应该创建一个实例，如下所示

static var shared:InAppPurchase = {
        return InAppPurchase()
    }()