参考数据链接：https://www.gdeten.com/static/common/help/three-nav-data.html
字段说明 [id] => 菜单ID [title] => 菜单名称 [url] => 菜单链接 [target] => 菜单何处打开链接文档 [icon] => 菜单图标 [current] => 菜单是否当前焦点【样式名】 [childs] => 子菜单
#判断有没有three_nav标签菜单
{notempty name="three_nav"}
{volist name='three_nav' id='item_three'}
{a href="{$item_three.url}" class="swiper-slide {$item_three.current}"}{$item_three.title}{/a}
{/volist}
{/notempty}