wordpress hero invalid argument supplied for foreach() - php

Question

I've noticed that the div image-16-8 from my hero.php file is not being displayed.
When I inspect element I get Invalid argument supplied for foreach() in
Here is the code:
<ul data-simple-slider>
<?php foreach ($images as $image): ?>
<li>
<div class="image-16-8" style="background-image: url(<?= $image->url; ?>); "></div>
</li>
<?php endforeach; ?>
</ul>
I've read a similiar question in which adding an if condition before foreach seems to fix the problem.
I'm not sure how to do this as I'm a beginner in php.
Any help is greatly appreciated!
Update Here is the full hero div -
<?php
function tbhHeroShortcode($atts)
{
$values = shortcode_atts(array(
'images' => '',
'first-line' => '',
'second-line' => '',
'video' => '',
'link' => '',
), $atts);
ob_start();
?>
<div class="hero">
<?
$images = decode_shortcode_data($values['images']);
if ($images): ?>
<ul data-simple-slider>
<?php foreach ($images as $image): ?>
<li>
<div class="image-16-8" style="background-image: url(<?= $image->url; ?>); "></div>
</li>
<?php endforeach; ?>
</ul>
<?php endif; ?>
<div class="hero-content">
<div class="hero-content-first-line">
<h1 class="header"><?= decode_shortcode_data($values['first-line']) ?></h1>
</div>
<h1 class="italic-header"><?= decode_shortcode_data($values['second-line']) ?></h1>
<div class="hero-content-cta">
<a class="hollow-button" href="<?= decode_shortcode_data($values['link']) ?>">Learn More</a>
</div>
</div>
<?php if (count($images) > 1): ?>
<div class="hero-controls">
<i class="fa fa-chevron-left hero-controls__left" aria-hidden="true"></i>
<i class="fa fa-chevron-right hero-controls__right" aria-hidden="true"></i>
</div>
<?php endif; ?>
</div>
<?php
$component = ob_get_contents();
ob_end_clean();
return $component;
}
add_shortcode('tbhHero', 'tbhHeroShortcode');

Answer 1

check if the $images is_iterable
if(is_iterable($images)) {
// foreach gets indented here
}
Also see the manual page for is_iterable http://php.net/manual/en/function.is-iterable.php
A nice polyfill for PHP5 users (let's hope they are not on <5.4)
<?php
if(!function_exists('is_iterable')) {
function is_iterable($var) {
return ( is_array( $var ) || ( $var instanceof Traversable ) );
}
}