如何使用Alamofire (swift)执行post以获取安全令牌作为返回值

import Alamofire

func fetchSecurityToken(completion: @escaping (String?, Error?) -> Void) {
    let url = "https://example.com/api/token"
    let parameters: [String: Any] = [
        "username": "your_username",
        "password": "your_password"
    ]
    
    Alamofire.request(url, method: .post, parameters: parameters)
        .validate()
        .responseJSON { response in
            switch response.result {
            case .success(let value):
                if let token = value["token"] as? String {
                    completion(token, nil)
                } else {
                    completion(nil, NSError(domain: "TokenError", code: 0, userInfo: nil))
                }
            case .failure(let error):
                completion(nil, error)
            }
        }
}

fetchSecurityToken { token, error in
    if let token = token {
        // 成功获取到安全令牌
        print("Security Token: \(token)")
    } else if let error = error {
        // 请求失败，处理错误
        print("Error: \(error.localizedDescription)")
    }
}