Swift - 完成处理程序代码未运行

Question

Im having trouble getting the code in my completion handler to run when I call it in my view. I have been trying to figure out why it is not working but had no luck. I believe it has to do with the DispatchQueue but im not sure. This is my view code im triyng to run. If anyone can explain why the code is not running, that would be much appreciated

struct SignIn: View {
    @Binding var userID: String
    @Binding var passcode: String
    @EnvironmentObject var authentication: AuthenticationCheck
    
    var body: some View {
        Button(action: {
            // Note: Works once data is decoded
            // Completion handler not running
            print("Button action")
            
            NetworkService.shared.signIn(username: userID, password: passcode) { (result) in
                switch result {
                case .success(let user):
                     // Does not run
                    print("This user last name is: \(userresult.login.userName)")
                    
                    authentication.updateValidation(success: true)
                    
                case .failure(let error):
                    print("The error is: \(error.localizedDescription)")
                }
            }
            
            
        }) {
            Text("Sign In")
                .multilineTextAlignment(.center)
                .padding()
        }
        .frame(width: 150.0, height: 43.0)
        .foregroundColor(.white)
        .cornerRadius(20)
        .disabled(userID.isEmpty || passcode.isEmpty)
        
    }
}

This is some of the code for my network call

func request<T: Codable>(endPoint: EndPoint, method: Method, parameters: [String: Any]? = nil, completion: @escaping(Result<T, Error>) -> Void) {
        // Creates a urlRequest
        guard let request = createRequest(endPoint: endPoint, method: method, parameters: parameters) else {
            completion(.failure(AppError.invalidUrl))
            return
        }
        
       
        
        let session = URLSession.shared
        
        session.dataTask(with: request) { data, response, error in
            var results: Result<Data, Error>?
            
            guard let httpResponse = response as? HTTPURLResponse, httpResponse.statusCode == 200 else {
                completion(.failure(AppError.badStatusCode))
                return
            }
            
            if let response = response {
                
                // Gets the JSESSIONID
                let cookieName = "JSESSIONID"
                if let cookie = HTTPCookieStorage.shared.cookies?.first(where: { $0.name == cookieName })  {
                    debugPrint("\(cookieName): \(cookie.value)")
                }
               
                print(response)
            }
            
            // Look into this
            if let data = data {
                results = .success(data)
    
            } else if let error = error {
                results = .failure(error)
                print("Server Error: \(error.localizedDescription)")
            }
            
            DispatchQueue.main.async {
                self.handleResponse(result: results, completion: completion)
            }
            
        }.resume()
    }
    
    
    private func handleResponse<T: Decodable>(result: Result<Data, Error>?, completion: (Result<T, Error>) -> Void) {
        guard let result = result else {
            completion(.failure(AppError.unknownError))
            return
        }
        
        switch result {
        
            case .success(let data):
                
                let decoder = JSONDecoder()
                // Decodes that json data
                do {
                    let json = try decoder.decode(T.self, from: data)
                    completion(.success(json)) 
                } catch {
                    print(error.localizedDescription)
                    
                }
                
                
            case .failure(let error):
                completion(.failure(error))
        }
    }

Im using this function to make the request

func signIn(username: String, password: Any, completion: @escaping (Result<LoginResponseData.Root.Result.Login.UserName.Name, Error>) -> Void) {
        let params = ["username": "\(username)", "password": "\(password)"]
        
        request(endPoint: .Login, method: .post, parameters: params, completion: completion)
    }
    

Answer 1

Usually when your escaping closure isn't being called, it usually means you have forgotten to call it in functions relating. Looking at your code, I think you need a completion in your case .success :

  case .success(let data):
            
            let decoder = JSONDecoder()
            // Decodes that json data
            do {
                let json = try decoder.decode(LoginResponseData.Root.self, from: data)
                // This prints
                print(json.result.login.userName.name.firstName)
            } catch {
                print(error.localizedDescription)
                
            }