yii\mail\MessageInterface::attach PHP Method

Attaches existing file to the email message.

public attach ( string $fileName, array $options = [] )
$fileName	string	full file name
$options	array	options for embed file. Valid options are: - fileName: name, which should be used to attach file. - contentType: attached file MIME type.

    public function attach($fileName, array $options = []);

MessageInterface