AFNetworking 2.0 add headers to GET request

Here's an example using AFNetworking 2.0

AFHTTPRequestOperationManager *manager = [AFHTTPRequestOperationManager manager];
manager.responseSerializer = [AFJSONResponseSerializer serializer];
manager.requestSerializer = [AFJSONRequestSerializer serializer];
[manager.requestSerializer setValue:@"calvinAndHobbesRock" forHTTPHeaderField:@"X-I do what I want"];

[manager GET:@"http://localhost:3000" parameters:nil success:^(AFHTTPRequestOperation *operation, id responseObject) {
    NSLog(@"JSON: %@", responseObject);
} failure:^(AFHTTPRequestOperation *operation, NSError *error) {
    NSLog(@"Error: %@", error);
}];

The key are the following 2 lines:

manager.requestSerializer = [AFJSONRequestSerializer serializer];
[manager.requestSerializer setValue:@"calvinAndHobbessRock" forHTTPHeaderField:@"X-I-do-what-I-want"];

The fantastic documentation for AFNetworking 2.0 makes this a little hard to find, but it is there. On the AFHTTPRequestSerializer is -setValue:forHTTPHeaderField:.

Alternatively, if you follow their recommended approach of creating a session manager that derives from AFHTTPSessionManager then that class can override a method to modify headers on each request -dataTaskWithRequest:completionHandler:. I use this to inspect requests and modify headers on a case-by-case basis, and prefer it to modifying the serializer as it keeps the responsibility for networking contained in that manager (and avoids mucking with singletons)

- (NSURLSessionDataTask *)dataTaskWithRequest:(NSURLRequest *)request completionHandler:(void (^)(NSURLResponse *, id, NSError *))completionHandler
{
    static NSString *deviceId;
    if(!deviceId)
    {
        deviceId = [[[UIDevice currentDevice] identifierForVendor] UUIDString];
    }

    NSMutableURLRequest *req = (NSMutableURLRequest *)request;
    // Give each request a unique ID for tracing
    NSString *reqId = [NSString stringWithFormat:@"%@+%@", deviceId, [[NSUUID UUID] UUIDString] ];
    [req setValue:reqId forHTTPHeaderField:"x-myapp-requestId"];
    return [super dataTaskWithRequest:req completionHandler:completionHandler];
}

adding response and request serializer solved my problem.

manager.responseSerializer = [AFJSONResponseSerializer serializer];
manager.requestSerializer = [AFJSONRequestSerializer serializer];

[manager.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
[manager.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Content-Type"];

I have used this form to make an appointment with a specific header.

AFHTTPRequestOperationManager *operationManager = [AFHTTPRequestOperationManager manager];
[operationManager.requestSerializer setValue:@"application/json" forHTTPHeaderField:@"Accept"];
[operationManager.requestSerializer setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Content-Type"];

[operationManager POST:url
            parameters:params
               success:^(AFHTTPRequestOperation *operation, id responseObject) {

                   if (success) {
                       success(responseObject);
                   }

               }
               failure:^(AFHTTPRequestOperation *operation, NSError *error) {

                   NSLog(@"Error: %@", [error description]);

               }
 ];