public function buildForm(FormBuilderInterface $builder, array $options)
{
    $builder
        ->add('titulo', null, array(
            'label' => 'Titulo del anuncio',
            'attr' => array('class' => 'form-control')
        ))
        ->add('descripcion', null, array(
            'label' => 'Descripción',
            'attr' => array('class' => 'form-control')
        ))
        ->add('fechaAnuncio', null, array(
            'label' => 'Fecha Anuncio: ',
            'widget' => 'single_text',
            'attr' => array('class' => 'form-control'),

        ))
        ->add('categoria', EntityType::class, array(
            'class' => Categoria::class,
            'label' => 'Categorias',

            'multiple' => true,
            'attr' => array('class' => 'form-control')
        ))
        ->add('imagenAnuncio', FileType::class, array(
            'mapped' => false,
            'label' => 'Imagenes',
            'attr' => array('class' => 'form-control-file', 'multiple' => 'multiple', 'data-show-upload' => 'true', 'data-show-caption' => 'true'),
            'required' => false

        ))
        ->add('precio', null, array(
            'label' => 'Precio',
            'attr' => array('class' => 'form-control')
        ));
}