URLSession没有获取SessionID Cookie

Question

如何在成功登录POST后获取所有cookie？我有以下代码登录到我的Django服务器，但是似乎从来没有创建session_id cookie，只有一个csrftoken cookie。目前，我是从HTTPCookieStorage.shared.cookies获取它们的，但是我感觉需要手动从URLSession.dataTask中提取它们？

登录：

func login() {
        let url = urlForEP(ep: loginEP)
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue(self.csrfToken, forHTTPHeaderField: "X-CSRFToken")
        let postData = [
            "username" : username,
            "password" : password
        ]
        let jsonData = try! JSONSerialization.data(withJSONObject: postData, options: [])
        let task = session.uploadTask(with: request, from: jsonData) { data, response, error in

            guard (response as! HTTPURLResponse).statusCode == 200 else {
                print("Failed to login")
                return
            }

            print("Successfully logged in!")
            self.printCookies()

            self.getItems()

        }
        task.resume()
    }

Cookie打印输出：

func printCookies() {
        for cookie in HTTPCookieStorage.shared.cookies! {
            print("\(cookie.name): \(cookie.value)")
        }
    }

结果：

csrftoken: lLgwYilYyqGzBfmkyvn8rZz6t6j8C8Ly7gwFxkcgAst1AODGukBCY6PGTXmTflmz