Swift 无法在范围内找到“”

Question

我遇到过这个问题几次，我试图将函数从一个 swift 文件传递到另一个文件，然后收到错误“在范围内找不到 '_'”。我想知道为什么会发生这种情况以及如何解决它？我尝试创建一个公共函数 public func fetchJokesAPI() ，同时将该函数的类设为 Observable 对象，以便我能够在我的 swift 文件中传递该函数。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，可以进一步参考该问题。

    //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

Answer 1

您收到错误是因为您需要类的实例来调用函数。

为了让你的代码工作，你可以做这样的事情，你的 viewController 接受一个服务

JokesWebService

像这样，更好的选择是在 viewModel 上使用该服务，如果你已经有一个服务，但如果没有的话，这应该可以解决问题让您开始：

import UIKit

class HomeViewController: UIViewController {
    
    @IBOutlet var tellAeAJokeButton: UIButton!

    private var service: JokesWebService!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        service = JokesWebService()
    }
    
    @IBAction func didPressBtn() {
        service.fetchJokesAPI() 
    }
}