Redirect if user isn't logged in (Wordpress) in functions.php

functions.php

<?php
      add_action('init','redirect_visitors');
      function redirect_visitors(){
            $current = $_SERVER['REQUEST_URI'];
            $wanted = '/wiki/login/';
      
            if(!is_user_logged_in()){
                if( $current != $wanted ){
                    wp_redirect($wanted);
                }
            }
      }
?>