PHP：Simple DOM Parser如何迭代这个html

I trying to iterate over this following html using simple html dom parser but not getting to next node.

<div class="category-products">
<ul class="products-grid">
    <li><a href="http://someurl.com">Text</a></li>
    <li><a href="http://someurl.com">Text</a></li>
    <li><a href="http://someurl.com">Text</a></li>
</ul>
<ul class="products-grid">
    <li><a href="http://someurl.com">Text</a></li>
    <li><a href="http://someurl.com">Text</a></li>
    <li><a href="http://someurl.com">Text</a></li>
</ul>
<ul class="products-grid">
    <li><a href="http://someurl.com">Text</a></li>
    <li><a href="http://someurl.com">Text</a></li>
    <li><a href="http://someurl.com">Text</a></li>
</ul>
</div>

I want to iterate over each li and a for ul.products-grid but i am not getting to next ul tag I have used this code yet.

require_once('simple_html_dom.php');
set_time_limit(0);
ini_set('memory_limit', '1024M');
$url='http://www.somesite.com';
$html = file_get_html($url);

if(is_object($html)){
    foreach ( $html->find('div.category-products') as $elem){
        $data = $elem->innertext;
        $strdata = str_get_html($data);
        foreach ($strdata->find('ul[class="products-grid"]') as $ul) {
                //not getting how to iterate over next ul tags
        }
        die;
    }
}

Any body having any idea please help to sort it out. Thanks

You're overcomplicating it:

foreach ( $html->find('div.category-products li a') as $a){
  // do something with $a
}

You may try this

$url='http://www.somesite.com';
$html = file_get_html($url);
if(is_object($html)){
    foreach ( $html->find('div.category-products .products-grid') as $ul){
        // To iterate al li tags use following
        foreach ( $ul->find('li') as $li )  echo $li. '<br />';
        // To iterate al a tags use following
        foreach ( $ul->find('li a') as $a ) echo $a. '<br />';
    }
}