How to detect 304 statusCode with Alamofire

Question

Is there a way to detect 304 Not Modified response with Alamofire 4? I find that Alamofire response.statusCode is always 200 even if server responded with 304.

Network call setup:

Alamofire 
    .request("http://domain.com/api/path", method: .get)
    .validate(statusCode: 200..<300)
    .validate(contentType: ["application/json"])
    .responseJSON { response in 
        print(response.response?.statusCode)
}

Alamofire response header

<NSHTTPURLResponse: 0x61800003e1c0> { URL: http://domain.com/api/path } { status code: 200, headers {
    "Access-Control-Allow-Headers" = "content-type, authorization";
    "Access-Control-Allow-Methods" = "GET, PUT, POST, DELETE, HEAD, OPTIONS";
    "Access-Control-Allow-Origin" = "*";
    "Cache-Control" = "private, must-revalidate";
    Connection = "keep-alive";
    "Content-Type" = "application/json";
    Date = "Mon, 23 Jan 2017 23:35:00 GMT";
    Etag = "\"f641...cbb6\"";
    "Proxy-Connection" = "Keep-alive";
    Server = "nginx/1.10.1";
    "Transfer-Encoding" = Identity;
} }

Server response

HTTP/1.1 304 Not Modified
Server: nginx/1.10.1
Connection: keep-alive
Access-Control-Allow-Origin: *
Access-Control-Allow-Headers: content-type, authorization
Access-Control-Allow-Methods: GET, PUT, POST, DELETE, HEAD, OPTIONS
Cache-Control: private, must-revalidate
ETag: "f641...cbb6"
Date: Mon, 23 Jan 2017 23:35:00 GMT

Possible duplicate of [Swift Alamofire: How to get the HTTP response status code](http://stackoverflow.com/questions/29131253/swift-alamofire-how-to-get-the-http-response-status-code) — Ahmad F, Jan 23 '17 at 22:43
[This](http://stackoverflow.com/questions/34737574/alamofire-returns-success-on-error-http-status-codes) also might be useful. — Ahmad F, Jan 23 '17 at 22:44
@AhmadF thank you for pointing out to relevant responses, they do not address the question at hand though — Digitech, Jan 24 '17 at 00:06

Rob · Accepted Answer · 2017-04-29T13:38:56.057

Since NSURLSessions default behavior is to abstract from cached 304 responses by always returning 200 responses (but not actually reloading the data), I first had to change the cachingPolicy as follows:

urlRequest.cachePolicy = .reloadIgnoringCacheData

Then, I adjusted the status codes of the validate function to accept 3xx responses and handled the codes accordingly:

Alamofire.request("https://httpbin.org/get")
        .validate(statusCode: 200..<400)
        .responseData { response in
            switch response.response?.statusCode {
                case 304?:
                    print("304 Not Modified")
                default:
                    switch response.result {
                    case .success:
                        print("200 Success")
                    case .failure:
                        print ("Error")
                    }
                }
            }

score 0 · Answer 2 · answered Jan 23 '17 at 22:18

0

You can use manual response validation with Alamofire as outlined here.

Alamofire.request("https://httpbin.org/get")
    .validate(statusCode: 200..<300)
    .validate(contentType: ["application/json"])
    .responseData { response in
        switch response.result {
        case .success:
            print("Validation Successful")
        case .failure(let error):
            print(error)
        }
    }

answered Jan 23 '17 at 22:18

CodeBender

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1

With custom validation `response.statusCode` is still 200 even though server responded with 304 – Digitech Jan 23 '17 at 22:25
Can you add the JSON object you receive to your question? – CodeBender Jan 23 '17 at 22:45
1

Alamofire returns cached version of JSON which is identical to a call with 200 status code – Digitech Jan 23 '17 at 23:45
@Digitech Have you modified the local caching policy? – CodeBender Jan 24 '17 at 01:11
Nope, using the default one CachePolicy.useProtocolCachePolicy. The only thing modified on URLRequest is set few headers – Digitech Jan 24 '17 at 01:46

How to detect 304 statusCode with Alamofire

2 Answers2