How to detect 304 statusCode with Alamofire - ios

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

Answer 1

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")
}
}
}

Answer 2

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)
}
}