add_filter( 'woocommerce_email_attachments', 'attach_pdf_file_to_customer_completed_email', 10, 3);
function attach_pdf_file_to_customer_completed_email( $attachments, $email_id, $order ) {
	if( $email_id === 'customer_processing_order' ){
        $attachments[] = generatePDF2( $order, get_current_user_id() );
	}

    return $attachments;
}