is any global way pass session vars to views or THE ONLY WAY IS when pass vars to vie

Code:

  <h2>Welcome Back, <?php echo $this->session->userdata('username'); ?>!</h2>

1    3.1.7
How this session var passed to view and get accessed directly from $this->session obj? is any global way pass session vars to views or THE ONLY WAY IS when pass vars to view from controller like $data below????

 $this->load->view('data', $data);

2   3.1.7
API JSON requests in codeigniter like this https://tech.yandex.com/translate/doc/dg...e-docpage/

in what page of manual exist more info about codeigniter json requests????