CookieManager::setCookie PHP Method

    public function setCookie($setCookie, $domain = null);

<?php

include_once '../config.php';
require_once ROOT_NAME . "/src/classes/LinkParser.php";
require_once ROOT_NAME . "/src/classes/CookieManager.php";
require_once ROOT_NAME . "/src/classes/SubredditsFactory.php";
require_once ROOT_NAME . "/src/classes/SubredditDownloader.php";
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $url = $_POST["subreddit"];
    try {
        $linkParser = new LinkParser($url);
        $cookieManager = new CookieManager($_COOKIE);
        $downloader = new SubredditDownloader($linkParser->getSubredditUrl());
        $idInCookie = $cookieManager->addSubreddit($linkParser);
        $cookieManager->setCookie();
        $subreddit = new Subreddit($downloader);
        echo json_encode(['id' => $idInCookie, 'subreddit' => $subreddit]);
    } catch (Exception $e) {
        echo json_encode($e->getMessage());
    }
} elseif ($_SERVER['REQUEST_METHOD'] === 'GET') {
    $id = $_GET["id"];
    try {
        $cookieManager = new CookieManager($_COOKIE);
        $subreddit = SubredditsFactory::create($cookieManager, $id);
        echo json_encode(['id' => $id, 'subreddit' => $subreddit]);
    } catch (Exception $e) {
        echo json_encode($e->getMessage());
    }
}