我遇到过这个问题几次，当我试图从一个swift文件传递一个函数到另一个swift文件时，我得到错误消息，"在作用域中找不到'_'"。我想知道为什么会发生这种情况，如何解决它？我试过创建一个公共函数，public func fetchJokesAPI（）、同时把这个函数的类做成一个Observable对象，这样我就可以在我的swift文件中传递这个函数，为什么编译器在作用域中找不到我的函数？下面是一些代码，以进一步提供参考的问题。

//Model

import Foundation

struct DecodingError: Error{}

struct JokesModel: Codable {
    let type: String
    let value: Value
}

// MARK: - Value
struct Value: Codable {
    let id: Int
    let joke: String
     
}





     
class JokesAPI {
    var session: URLSession?
 
  // MARK: Getting random jokes from API endpoint

func fetchJokes() {
    guard let url = URL(string: "https://api.icndb.com/jokes/random/") else {
        print("Cannot generate URL")
        return
    }
     var request = URLRequest(url: url)
    
    request.httpMethod = "GET"
    
    let task = URLSession.shared.dataTask(with: request) { data, response, error in
        if let error = error {
            print(error.localizedDescription)
            return
        }
        
        guard (response as? HTTPURLResponse) != nil else {
            print("No Response")
            return
        }
          struct JokesResponse: Decodable {
            let data: [JokesModel]
        }

        guard let data = data, let dataString = String(data: data, encoding: .utf8)
        else {
            print("No Data")
            return
        }
        do {
            let jokeResponse = try JSONDecoder().decode(JokesResponse.self, from: data)
            print(jokeResponse.data)
         } catch {
           print("Error decoding joke response:", error)
              
            
        }
        
    }
    task.resume()
}
 
}



// Another Swift File that is a Coco touch file. 



   

 import UIKit
    import Foundation
    
    class HomeViewController: UIViewController {
        
       private let service = JokesAPI()
        private var joke: [JokesModel]?
        
       
        @IBOutlet var tellAeAJokeButton: UIButton!
        @IBOutlet var jokeLabel: UILabel!
        
        override func viewDidLoad() {
            super.viewDidLoad()
            service.fetchJokes()
        }
        
        @IBAction func didPressBtn() {
            
            // MARK: Actions for both fetching a joke from the API, & Text-Speech using AI Voice
            service.fetchJokes()
            joke = [JokesModel]()
            jokeLabel.text = JokesModel().joke
            // Value of type 'JokesModel' has no member 'joke'
            // Missing argument for parameter 'from' in call