POST with NSURLSession in RubyMotion

nsurlsession_post.rb

def session
  return @session if @session
  configuration = NSURLSessionConfiguration.defaultSessionConfiguration.tap do |conf|
    conf.HTTPAdditionalHeaders = {'Accept'=>'application/json',
                                  'Accept-Language'=>'en',
                                  'User-Agent'=> user_agent}
  end
  @session = NSURLSession.sessionWithConfiguration(configuration)
  @session
end

def post_example(aURLString, aDictionary={}, &block)
  aDictionary = aDictionary.mutableCopy
  aDictionary['apikey'] = api_key

  request = NSMutableURLRequest.requestWithURL(NSURL.URLWithString("#{url_prefix_v2}#{aURLString}")).tap do |v|
    v.HTTPMethod = 'POST'
  end
  data = NSJSONSerialization.dataWithJSONObject(aDictionary, options: 0, error: nil)
  task = session.uploadTaskWithRequest(request, fromData: data, completionHandler: proc {|data, response, error|
    handle_api_result(data, error, &block)
  })
  task.resume
end