gistfile1.txt

add_filter( 'propertyhive_search_form_fields_after', 'add_form_control_class_to_form_fields', 99 );
function add_form_control_class_to_form_fields($fields)
{   
    $new_fields = array();
    foreach ( $fields as $field )
    {
        $field['class'] = 'form-control';
        $new_fields[] = $field;
    }
		
    return $new_fields; // return the fields
}