The following code is what works using the explode() function. How is it possible to combine echo for an unknown number of URLs?
<div id="slider" class="flexslider">
<ul class="slides">
<?php
$string = get_field( 'other' );
$split = explode ( '|', $string );
echo "<li><img src='{$split[0]}' /></li>";
echo "<li><img src='{$split[1]}' /></li>";
echo "<li><img src='{$split[2]}' /></li>";
echo "<li><img src='{$split[3]}' /></li>";
var_dump(the_field( 'other' ));
?>
</ul>
</div>
