Hi,I try to use NSURLSession with HTTPAdditionalHeaderMy code setting headers in requestlet URL = NSURL(string: (hostName)(uri))! let request = NSMutableURLRequest(URL: URL) request.HTTPMethod = method request.HTTPBody = NSJSONSerialization.dataWithJSONObject(params, options: nil, error: nil) request.setValue(application/vnd.myapp.v2, forHTTPHeaderField: Accept) request.setValue(application/json, forHTTPHeaderField: Content-Type) request.setValue(gzip, forHTTPHeaderField: Content-Encoding)And with POST request it's produce this on my server :Parameters: {email=>me@email.com, password=>[FILTERED], subdomain=>api, session=>{email=>me@email.com, password=>[FILTERED]}}With NSURLSession, setting headers with HTTPAdditionalHeaders of NSURLSessionConfigurationvar headers = [ Accept: application/vnd.myapp.v2, Content-Type: application/json, Content-Encoding: gzip, ] let request = NSMutableURLRequest(URL: NSURL(string: (hostName)(uri))!) request.HTTPMethod = method request.HTTPBody = NSJSONS