how to use Alamofire with custom headers

According to the official documentation, modifying the session configuration is not recommended:

This is not recommended for Authorization or Content-Type headers. Instead, use URLRequestConvertible and ParameterEncoding, respectively.

So an example usage of URLRequestConvertible for authorization would be:

enum Router: URLRequestConvertible {    static let baseUrlString = "some url string"    case Get(query: String)    var URLRequest: NSMutableURLRequest {        let (path: String, parameters: [String: AnyObject]?) = {            switch self {            case .Get(let query):                return ("/get", ["q": query])            }        }()        let URL = NSURL(string: Router.baseUrlString)!        let URLRequest = NSMutableURLRequest(URL: URL.URLByAppendingPathComponent(path))        // set header fields        URLRequest.setValue("a", forHTTPHeaderField: "Authorization")        let encoding = Alamofire.ParameterEncoding.URL                return encoding.encode(URLRequest, parameters: parameters).0    }}

and when you want to make a request:

Manager.sharedInstance.request(Router.Get(query: "test"))

More info about URLRequestConvertible: https://github.com/Alamofire/Alamofire#urlrequestconvertible

Old Answer

As of Alamofire v1.0 Pers answer no longer works. In the new version additional headers should be added to the HTTPAdditionalHeaders property of NSURLSessionConfiguration

Alamofire.Manager.sharedInstance.session.configuration.HTTPAdditionalHeaders = ["Authorization": authorizationToken]

More info here: https://github.com/Alamofire/Alamofire/issues/111

For headers that change from request to request, you can pass them directly to the request method. From the docs:

Adding a custom HTTP header to a Request is supported directly in the global request method. This makes it easy to attach HTTP headers to a Request that can be constantly changing.

And the example given:

    let headers = [        "Authorization": "Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==",        "Content-Type": "application/x-www-form-urlencoded"    ]    Alamofire.request(.GET, "https://httpbin.org/get", headers: headers)             .responseJSON { response in                 debugPrint(response)             }

If, however, you wish to set headers that do not change, it is recommended that you do so on the NSURLConfiguration object, as others have mentioned here.

At this time , Swift 3.0 , Xcode 8.x, Alamofire 4.x:

You can use custom header as below:

let headers: HTTPHeaders = [    "Authorization": "Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==",    "Accept": "application/json"]Alamofire.request("https://httpbin.org/headers", headers: headers).responseJSON { response in    debugPrint(response)}

For reference