populate city from rajaongkir.com API - Opencart

custom.tpl

<select name="custom_city_id" id="input-city" class="form-control">
  <option value="0"><?php echo $text_none; ?></option>
  <?php foreach ($cities as $value) { ?>
  <?php if ($value->city_id == $custom_city_id) { ?>
  <option value="<?php echo $value->city_id; ?>" selected="selected"><?php echo $value->city_name; ?></option>
  <?php } else { ?>
  <option value="<?php echo $value->city_id; ?>"><?php echo $value->city_name; ?></option>
  <?php } ?>
  <?php } ?>
</select>