Advanced Custom Fields - Nested Repeater

acf-nest-repeat.txt

    <?php if( have_rows('grade_repeat') ): ?>

        <?php while ( have_rows('grade_repeat') ) : the_row(); ?>

            <h3><?php the_sub_field('class_level'); ?></h3>

              <?php if( have_rows('class_repeater') ): ?>

                    <?php while( have_rows('class_repeater') ): the_row(); ?>

                       <ul>
                         <li><?php the_sub_field('class_date'); ?> - <?php the_sub_field('class_name'); ?></li>
                       </ul>
                    <?php endwhile; ?>

                  <?php endif; ?>

        <?php endwhile; ?>

      <?php else : ?>

      <?php endif; ?>