public function get_url( $size ) {
		$url = null;
		if ( isset( $this->struct['return_type'] ) && 'url' === $this->struct['return_type'] ) {
			$url = $this->get_value();
		} else {
			$data = wp_get_attachment_image_src( $this->get_value(), $size );
			if ( ! empty( $data ) ) {
				$url = $data[0];
			}
		}

		return $url;
	}