Add category of each element in a form - symfony

Question

Well, currently I have something like this:
And I would like to add categories appears before filters, like this:
My form code:
$formFilter = $this->createFormBuilder()
->add('_', EntityType::class,array(
'class' => 'loicFilterBundle:Filter',
'multiple' => true,
'expanded' => true,
'choice_label' => function($value) {
return ($value->getName());
},
))
->add('Appliquer filtres', SubmitType::class)
->getForm();
How to add categories before ?
Thanks for help :) .
EDIT:
I finally succeeded by doing it in the twig view(but also need to let group by in the controller):
{{ form_start(form) }}
{% for group in form.filterfilter.vars.choices %}
<div class="col-xs-2">
<h3>{{ group.label }}</h3>
{% for value in group.choices %}
{{ form_widget(form.filterfilter[value.value]) }}
{% endfor %}
</div>
{% endfor %}
{{ form_end(form) }}

Answer 1

What about using the group_by option (see doc) ?
Something like :
$formFilter = $this->createFormBuilder()
->add('_', EntityType::class,array(
'class' => 'loicFilterBundle:Filter',
'multiple' => true,
'expanded' => true,
'choice_label' => function($value) {
return $value->getName();
},
'group_by' => function($value) {
return $value->getCategory()->getName();
},
))
->add('Appliquer filtres', SubmitType::class)
->getForm();