AFNetworking returns a _NSCFData object instead of JSON - afnetworking

Question

I'm sending the following message to an instance of AFHTTPClient. I expect the success block to be sent a Foundation object (a dictionary) but the debugger shows me that JSON is a _NSCFData object. This question on SO states that I need to set the Accept header to 'application/json'. Well, I'm doing that but AFNetworking still is not decoding the JSON in the response body. If I decode the json myself using NSJSONSerialization I get an NSDictionary as I expect. What am I doing wrong?
[client setDefaultHeader:#"Accept" value:#"application/json"];
[client postPath:#"/app/open_connection/"
parameters:params
success:^(AFHTTPRequestOperation *operation, id JSON) {
NSLog(#"successful login! %#", [JSON valueForKeyPath:#"status"]);
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSLog(#"error opening connection");
NSAlert *alert = [NSAlert alertWithError:error];
[alert runModal];
}
];
Note: I'm programming the server in Python using Django. The content type of the response is 'application/json'

Answer 1

When you're working with AFHTTPClient and a JSON API, you will typically need to set all three of these settings:
httpClient.parameterEncoding = AFJSONParameterEncoding;
[httpClient setDefaultHeader:#"Accept" value:#"application/json"];
[httpClient registerHTTPOperationClass:[AFJSONRequestOperation class]];
Now when you make requests using your client, it will know to parse the response as JSON.
[httpClient postPath:#"/app/open_connection/"
parameters:params
success:^(AFHTTPRequestOperation *operation, id response) {
NSLog(#"JSON! %#", response);
}
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
}];
Here's a trick that I discovered as well. In the NSError object you can parse it and retrieve the error message (if the HTTP response had a JSON error message):
failure:^(AFHTTPRequestOperation *operation, NSError *error) {
NSDictionary *JSON =
[NSJSONSerialization JSONObjectWithData: [error.localizedRecoverySuggestion dataUsingEncoding:NSUTF8StringEncoding]
options: NSJSONReadingMutableContainers
error:nil];
failureCallback(JSON[#"message"]);
}

Answer 2

Try this ... I think there maybe something wrong with your client settings.
NSMutableURLRequest *request = [client requestWithMethod:#"POST" path:#"/app/open_connection/" parameters:params];
AFJSONRequestOperation *operation =
[AFJSONRequestOperation JSONRequestOperationWithRequest:request
success:^(NSURLRequest *request, NSHTTPURLResponse *response, id JSON) {
NSLog(#"successful login! %#", [JSON valueForKeyPath:#"status"]);
}
failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error, id JSON) {
NSLog(#"error opening connection");
NSAlert *alert = [NSAlert alertWithError:error];
[alert runModal];
}];
[operation start];