Example of a Bootstrap 4 Accordion, using Laravel blade template and ACF Pro repeating fields and sub-fields.
@if ( get_field('faq') )
@while ( has_sub_field('faq') )
<p class="title">@php the_sub_field('faq_title') @endphp</p>
@php $accordionName = get_sub_field('faq_title'); $accordionName = strtolower($accordionName); $accordionName = str_replace(' ', '-', $accordionName); $accordionName = str_replace('&', '', $accordionName) @endphp
@if ( get_sub_field('faq_repeater') ) @php $i = 0 @endphp
<div class="accordion" id="accordion-@php echo $accordionName @endphp">
@while ( has_sub_field('faq_repeater') )
<div class="card">
<div class="card-header" id="heading-@php echo $i @endphp">
<h5 class="mb-0">
<button class="btn btn-link @if($i > 0) collapsed @endif" type="button" data-toggle="collapse" data-target="#collapse-@php echo $accordionName . '-' . $i @endphp" aria-expanded="@if($i > 0) false @else true @endif" aria-controls="collapse-@php echo $accordionName . '-' . $i @endphp">
@php the_sub_field('question') @endphp
</button>
</h5>
</div>
<div id="collapse-@php echo $accordionName . '-' . $i @endphp" class="collapse" aria-labelledby="heading-@php echo $accordionName . '-' . $i @endphp" data-parent="#accordion-@php echo $accordionName @endphp">
<div class="card-body">
@php the_sub_field('answer') @endphp
</div>
</div>
</div>
@php $i++ @endphp @endwhile
</div>
@endif
@endwhile
@endif