beforeFilter() method in APIController()

gistfile1.txt

public function beforeFilter(Event $event)
{
    parent::beforeFilter($event);

    $this->response->cors($this->request)
    ->allowOrigin(['http://adunit.adphenom.com/'])
    ->allowMethods(['GET', 'POST'])
    ->allowHeaders(['X-API-Auth-Token'])
    ->allowCredentials()
    ->exposeHeaders(['Link'])
    ->maxAge(300)
    ->build();
}