我使用的是二十一主题，下面是它用来注册和显示菜单的代码。

In functions.php:

function twentytwelve_setup() {

    ...

    // This theme uses wp_nav_menu() in one location.
    register_nav_menu( \'primary\', __( \'Primary Menu\', \'twentytwelve\' ) );

    ...

}
add_action( \'after_setup_theme\', \'twentytwelve_setup\' );

In header.php:

<nav class="site-navigation main-navigation" role="navigation">
    <?php wp_nav_menu( array( \'theme_location\' => \'primary\' ) ); ?>
</nav>

输出代码如下所示：

<nav class="site-navigation main-navigation" role="navigation">
    <div class="menu-main-menu-container">
        <ul id="menu-main-menu" class="menu">

            <li id="menu-item-9" class="menu-item menu-item-type-custom menu-item-object-custom current-menu-item current_page_item menu-item-home menu-item-9">
                <a href="http://aahank.com/">Home</a>
            </li>

            <li id="menu-item-12" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-12">
                <a href="http://example.com/">About</a>
            </li>

        </ul>
    </div>
</nav>

但我想修改输出，以便搜索框可以作为如下菜单项集成到导航菜单中：

<nav class="site-navigation main-navigation" role="navigation">
    <div class="menu-main-menu-container">
        <ul id="menu-main-menu" class="menu">

            <li id="menu-item-9" class="menu-item menu-item-type-custom menu-item-object-custom current-menu-item current_page_item menu-item-home menu-item-9">
                <a href="http://aahank.com/">Home</a>
            </li>

            <li id="menu-item-12" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-12">
                <a href="http://example.com/">About</a>
            </li>

            <li id="menu-item-13" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-13">

                <!-- Search box inside nav as a menu item -->
                <form method="get" id="searchform" action="/">
                    <label for="s" class="assistive-text">Search</label>
                    <input type="text" class="field" name="s" id="s" placeholder="Search" />
                    <input type="submit" class="submit" name="submit" id="searchsubmit" value="Search" />
                </form>

            </li>

        </ul>
    </div>
</nav>

我该怎么做呢？我需要一两个代码支持的指针。也欢迎用汤匙喂食P

function wpa_58902($items){
    $search = \'<li class="search">\';
    $search .= \'<form method="get" id="searchform" action="/">\';
    $search .= \'<label for="s" class="assistive-text">Search</label>\';
    $search .= \'<input type="text" class="field" name="s" id="s" placeholder="Search" />\';
    $search .= \'<input type="submit" class="submit" name="submit" id="searchsubmit" value="Search" />\';
    $search .= \'</form>\';
    $search .= \'</li>\';

    return $items . $search;
}
add_filter(\'wp_nav_menu_items\',\'wpa_58902\');

</hgroup>
<div class="header-search"><?php get_search_form(); ?></div>

.header-search {
    float: right;
    margin-top: -50px;
}
@media (max-width: 650px) {
    .header-search {
        margin-top:5px;
        text-align:center;
        float:none;
    }
    .main-navigation  {
        clear:both;
    }
}