How do we add an authentication header to the upload function of Alamofire 4.0?
below is the sample code, however I see no way in adding a header to the function.
Alamofire.upload(
    multipartFormData: { multipartFormData in
        multipartFormData.append(unicornImageURL, withName: "unicorn")
        multipartFormData.append(rainbowImageURL, withName: "rainbow")
    },
    to: "https://httpbin.org/post",
    encodingCompletion: { encodingResult in
        switch encodingResult {
        case .success(let upload, _, _):
            upload.responseJSON { response in
                debugPrint(response)
            }
        case .failure(let encodingError):
            print(encodingError)
        }
    }
)
Previous version of alamofire supported adding header directly, but not the new one. Any ideas?
 
    