如何从 Objective C 项目 App Delegate 调用 Swift？

问：

此代码来自 Swift 项目 App 委托。它用于帮助配置具有可发布密钥的 Stripe。

//Appdelegate.swift
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: 
[UIApplicationLaunchOptionsKey: Any]?) -> Bool 
{
//The code helps configure Stripe with a publishable key.
STPPaymentConfiguration.shared().publishableKey = Constants.publishableKey
...
}

将 Swift 行添加到 Objective C App Delegate 后，构建 App 时会显示两个错误

//AppDelegate.h
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions
{
STPPaymentConfiguration.shared().publishableKey = Constants.publishableKey

Property 'shared' not found on object of type 'STPPaymentConfiguration'
Use of undeclared identifier 'Constants'

这是在编译时出现类似的错误，之前被添加到演示 Swift 函数 MockApiClient 中。是否应该将其添加到其他地方？我尝试在此处的答案中提到的枚举中添加，但无济于事。@objc@objc

//Constants.swift 
//This is the file the original Swift app delegate accesses
import Foundation

  enum Constants {
  static let publishableKey = "pk_live_..."
  static let baseURLString = "http://54.33.123.227:1234"
  static let defaultCurrency = "usd"
  static let defaultDescription = "Receipt" //change to describe actual app & charge
  }

采取的步骤：

1. 打开 Objective C 项目并创建桥接标头

2. 在 Swift 中创建了一个演示类，同时仍在 Obj C 项目中，以确保可以使用它，在本例中，用于在加载视图时从 Objective C 文件打印。具体派生自 NSObject。将覆盖添加到初始值设定项并使用前缀。@objc

   //  MockApiClient.swift
   import Foundation
   class MockApiClient: NSObject
   {
   override init()
   {
   print("Initializer called in Mock API client")
   }
   @objc func executeRequest()
   {
   print("The execute request has been called in the Mock API Client")
   }
   }
   
   //ViewController.h
   //Prints the Swift request written in the MockApiClient the the view loads
   
   @implementation ViewController
   - (void)viewDidLoad
   {
   [super viewDidLoad];
   // Do any additional setup after loading the view, typically from a nib.
   MockApiClient *client = [MockApiClient new];
   [client executeRequest];
   }
   

3. 将导入复制到自动生成的文件中，以将其中的 Objective C 暴露给 swift#import "ViewController.h"project-Bridging-Header.h

4. 将必要的 Swift 文件添加到 Objective C 项目中，以便可以找到Constants.publishablekeyConstants.swift

如何将此 Swift App 委托代码添加到 Objective C 项目的 App 委托中？

编辑：添加到声明时出错@objcenumConstants.swift