Битрикс. Вывести дерево разделов и элементов

gistfile1.phtml

    <?
    $iblock = 3;
    $res = CIBlockSection::GetList(
        Array("LEFT_MARGIN" => "ASC"),
        Array("IBLOCK_ID" => $iblock, "ACTIVE" => "Y", "GLOBAL_ACTIVE" => "Y"),
        true,
        Array("ID", "NAME", "DESCRIPTION", "PICTURE","SECTION_PAGE_URL")
    );


    while ($arSection = $res->GetNext()) {

        $iCnt2 = CIBlockElement::GetList(array(), array("IBLOCK_ID" => $iblock, "ACTIVE" => "Y", "SECTION_ID" => $arSection['ID']), array());
        if ($iCnt2 == 0) {
            echo '<b><a href="' . $arSection['SECTION_PAGE_URL'] .'">' .$arSection['NAME'] . "</a></b><br>";
            continue;
        }

        echo '<ul><b><a href="' . $arSection['SECTION_PAGE_URL'] .'">' .$arSection['NAME'] . "</a></b><br>";
        $arSelect = Array("ID", "NAME", "DATE_ACTIVE_FROM");
        $iCnt = CIBlockElement::GetList(array(), array("IBLOCK_ID" => $iblock, "ACTIVE" => "Y", "SECTION_ID" => $arSection['ID']), false, Array(), $arSelect);


        while ($ob = $iCnt->GetNextElement()) {
            $arFields = $ob->GetFields();

            foreach ($arResult['ITEMS'] as $cell => $arElement) {
                if ($arFields['ID'] == $arElement['ID']) {
                    echo '<li><a href="' . $arElement['DETAIL_PAGE_URL'] .'">' . $arElement['NAME'] . "</a></li>";
                }
            }
        }
        echo "</ul>";
    }

    ?>