会话，所以你可以返回到上一页，类似以下的行：

you'd need to store your request URI in a session for this, so you can return to the previous page, something along the lines of:

function __construct()
{
    parent::__construct();
    if($this->session->userdata('logged_in')!=TRUE) {
        $this->load->helper('url');
        $this->session->set_userdata('last_page', current_url());
        redirect('/login');
    }
}

...您可以使用会话数据重定向回

... you can then use session data to redirect back