$user_id = 1;
$this->load->helper('url');
$this->load->library('curl');
$this->curl->create(site_url('api/example/users/id/'.$user_id.'/format/json'));
// Optional, delete this line if your API is open.
$username = 'admin';
$password = '1234';
$this->curl->http_login($username, $password);
$result = $this->curl->get()->execute();
bool(false)