attach

// Create your file contents in the normal way, but don't write them to disk
$data = create_my_pdf_data();

// Create the attachment with your data
$attachment = Swift_Attachment::newInstance($data, 'my-file.pdf', 'application/pdf');

// Attach it to the message
$message->attach($attachment);


// You can alternatively use method chaining to build the attachment
$attachment = Swift_Attachment::newInstance()
  ->setFilename('my-file.pdf')
  ->setContentType('application/pdf')
  ->setBody($data)
  ;