How do I replace front-end views with JSONs in Codeigniter 3?

Great. It works as desired. 

How can I make the json pretty, from the controller?

https://www.php.net/manual/en/function.json-encode.php

PHP Code:

public function index() {
   $data['something'] = 'whatever is appropriate';
   $this->output->set_content_type('application/json')->set_output(json_encode($data,JSON_PRETTY_PRINT));
}