问方法在从Combine Future Publisher接收数据之前结束

EN

import Cocoa
import Combine

func prepareURLRequest(for url: URL) -> URLRequest {
    let request = URLRequest(url: url)
    var token = "token"

    print("start value: \(token)")

    let subscription = Token()
    subscription.getToken()
        .sink(receiveCompletion: { _ in
        print("subscription completed")
    }, receiveValue: { value in
        token = value
        print("value received: \(token)")
    })

    print("new value: \(token)")

    // attach received token to request
    return request
}


class Token {
    let token = PassthroughSubject<String,Never>()

    func verify() -> Bool {
        // TODO: Token verification logic
        Bool.random()
    }

    func getToken() -> AnyPublisher<String,Never> {
        return Future<String, Never> { promise in
            if self.verify() {
                let url = URLRequest(url: URL(string: "http://avatars.io/twitter/twostraws")!)
                URLSession.shared.dataTask(with: url) { data, response, error in
                    print("Data Task started")
                    if let error = error {
                        print("error \(error)")

                    }
                    guard let data = data else {
                        preconditionFailure("data error")
                    }
                    guard let response = response as? HTTPURLResponse else {
                        preconditionFailure("response error")
                    }

                    print("data task received response with code: \(response.statusCode)")
                    promise(.success("\(response.statusCode)"))
                }.resume()
            } else {
                print("keychain path")
                sleep(2)
                promise(.success("kwychain path success"))
            }
        }.eraseToAnyPublisher()
    }
}

let url = URL(string: "http://avatars.io/twitter/twostraws")!
let request = prepareURLRequest(for: url)