swift - 如何在 Swift 中存储 JSON 发布响应的一个特定元素

Question

我有一个快速程序，可以创建一个成功的 JSON 帖子到 Rails 应用程序。这是回复:

Optional(<NSHTTPURLResponse: 0x604000226280> { URL: http://groupsyncenv.rtimfc7m2.eu-west-1.elasticbeanstalk.com/login_post } { Status Code: 200, Headers {
"Cache-Control" =     (
    "max-age=0, private, must-revalidate"
);
Connection =     (
    close
);
"Content-Length" =     (
    618
);
"Content-Type" =     (
    "application/json; charset=utf-8"
);
Date =     (
    "Wed, 24 Jan 2018 17:57:52 GMT"
);
Etag =     (
    "W/\"c34b1ba0f3cfbd53ef65a30eddd47c50\""
);
Server =     (
    "nginx/1.12.1"
);
Via =     (
    "1.1 m00180A4E4E3C (squid/3.5.23)"
);
"X-Cache" =     (
    "MISS from m00180A4E4E3C"
);
"X-Cache-Lookup" =     (
    "MISS from m00180A4E4E3C:3128"
);
"X-Content-Type-Options" =     (
    nosniff
);
"X-Frame-Options" =     (
    SAMEORIGIN
);
"X-Request-Id" =     (
    "9bf3c1fa-e362-4d59-8396-8540981f1d36"
);
"X-Runtime" =     (
    "0.092878"
);
"X-XSS-Protection" =     (
    "1; mode=block"
);

我从这段代码中需要的只是与响应“X-Request-Id”关联的数字，但我不知道该怎么做。我的快速程序如下:

func loginPost(){

    let headers = [
        "Content-Type": "application/json",
        "Cache-Control": "no-cache",
        "Postman-Token": "b5468cec-292a-6c60-d195-6e270909e54b"
    ]
    let parameters = [
        "email": "sample@email.com",
        "password": "password123"
        ] as [String : Any]

    let postData = try? JSONSerialization.data(withJSONObject: parameters, options: [])
    guard let data = postData else {
        return
    }

    let request = NSMutableURLRequest(url: NSURL(string: "http://groupsyncenv.rtimfc7um2.eu-west-1.elasticbeanstalk.com/login_post")! as URL,
                                      cachePolicy: .useProtocolCachePolicy,
                                      timeoutInterval: 10.0)
    request.httpMethod = "POST"
    request.allHTTPHeaderFields = headers
    request.httpBody = postData as? Data

    let session = URLSession.shared
    let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
        if (error != nil) {
            print(error)
        } else {
            let httpResponse = response as? HTTPURLResponse
            print(httpResponse)
        }
    })

    dataTask.resume()

}

如您所见，我只是打印了 Http 响应，我知道这是错误的，但我不知道如何访问此处的各个元素。预先感谢您的帮助!

Answer 1

通过调用 response.allHeaderFields(它是一个 )将 URLResponse 对象转换为 HTTPURLResponse 后，您可以简单地访问 HTTP header 字典，因此您可以使用订阅来获取特定键对应的值。

一些通用建议:不要使用旧的 Foundation 数据类型，除非您有充分的理由这样做。使用他们的原生 Swift 替代品。当您在创建 Foundation 对象后立即将它们转换为其 Swift 替代方案时尤其如此，因为 Swift API 需要 Swift 类型，例如 URLRequest 而不是 NSMutableURLRequest 和 URL 而不是 NSURL。

let headers = [
    "Content-Type": "application/json",
    "Cache-Control": "no-cache"
]
let parameters = [
    "email": "sample@email.com",
    "password": "password123"
    ] as [String : Any]

let postData = try? JSONSerialization.data(withJSONObject: parameters, options: [])

var request = URLRequest(url: URL(string: "http://groupsyncenv.rtimfc7um2.eu-west-1.elasticbeanstalk.com/login_post")!, cachePolicy: .useProtocolCachePolicy, timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData

URLSession.shared.dataTask(with: request, completionHandler: { data, response, error in
    if (error != nil) {
        print(error!)
    } else if let response = response as? HTTPURLResponse {
        let requestId = response.allHeaderFields["X-Request-Id"] as? String
        print(requestId)
    }
}).resume()