BlogPost::addCategory

private function addCategory($blogPostId, array $fields)
{
	if (!empty($fields["CATEGORY_ID"]))
	{
		CBlogPostCategory::deleteByPostID($blogPostId);

		$categoryIds = explode(",", $fields["CATEGORY_ID"]);
		foreach ($categoryIds as $categoryId)
		{
			CBlogPostCategory::add([
				"BLOG_ID" => $fields["BLOG_ID"],
				"POST_ID" => $blogPostId,
				"CATEGORY_ID" => $categoryId
			]);
		}
	}
}