yii2: make checkbox to be checked

I guess this checkbox will be checked only if $model->order property take true value and if it has false (0 or null or false etc) value - field will be unchecked.

if your are setting an external value in checkbox.

<?php $model->order = "02256"; ?>
<?= $form->field($model, "order")->checkbox(['value' => "02256"]); ?>