public function getAssetsUrl()
    {
        if (isset($this->_assetsUrl)) {
            return $this->_assetsUrl;
        } else {
            $forceCopyAssets = $this->getApi()->forceCopyAssets;
            $path = Yii::getPathOfAlias('yiiwheels');
            $assetsUrl = Yii::app()->assetManager->publish(
                $path . DIRECTORY_SEPARATOR . 'assets',
                false,
                -1,
                $forceCopyAssets
            );

            return $this->_assetsUrl = $assetsUrl;
        }
    }