<?php
        while ( has_ddl_repeater('slider') ) : the_ddl_repeater('slider');  // loop through all the fields array
    ?>
            <span>
                <?php the_attachment_sub_field( 'slide_url', 'square'); ?>
            </span>
    <?php
        endwhile;
        ddl_rewind_repeater('slider'); // set the index to zero for later use
    ?>