CODE EXAMPLE FOR PHP

acf repeater

<?php
/**
 * Field Structure:
 *
 * - parent_repeater (Repeater)
 *   - parent_title (Text)
 *   - child_repeater (Repeater)
 *     - child_title (Text)
 */
if( have_rows('parent_repeater') ):
    while( have_rows('parent_repeater') ) : the_row();

        // Get parent value.
        $parent_title = get_sub_field('parent_title');

        // Loop over sub repeater rows.
        if( have_rows('child_repeater') ):
            while( have_rows('child_repeater') ) : the_row();

                // Get sub value.
                $child_title = get_sub_field('child_title');

            endwhile;
        endif;
    endwhile;
endif;