auto generate attachment file missing in wp_mail() - wordpress

Question

I am trying to send a mail with an attachment which is generating automatically according to the subscription option. But every time the mail is being sent (in Spam) but the attachment is not. I searched to this topic here but all the solutions are related to the 'uploads' folder.
Here is my code ..
require ( ABSPATH . 'pdfcrowd.php');
try
{
// create an API client instance
$client = new Pdfcrowd("apiname", "apikay");
// convert a web page and store the generated PDF into a $pdf variable
$pdf = $client->convertFile( ABSPATH . 'invoice_html.php');
// set HTTP response headers
header("Content-Type: application/pdf");
header("Cache-Control: max-age=0");
header("Accept-Ranges: none");
header("Content-Disposition: attachment; filename=\"invoice.pdf\"");
//$to = $invoice_email;
$to = "moyen#gmail.com";
$subject = "Invoice for your online package.";
$message = "Message Body Invoice for your online package. Invoice for your online package. Invoice for your online package";
$headers = array('Content-Type: text/html; charset=UTF-8','From: My Site Name <uddin#gmail.com');
$attachments = $pdf;
// send the generated PDF
//echo $attachments;
$wp_mail = wp_mail( $to, $subject, $message, $headers, $attachments );
}
catch(PdfcrowdException $why)
{
echo "Pdfcrowd Error: " . $why;
}
any help?
N.B:Since I managed to output the pdf file in the browser to save but I would like to save this pdf file in a directory and then will send as attachment. What will be the best with this code above ?
Thanks

Answer 1

Finally I am able to send the pdf in email by the following modification code below....
1. First I just save the converted pdf in the uploads folder then
2. I take the pdf for the attachments
require ( ABSPATH . 'pdfcrowd.php');
try
{
// create an API client instance
$client = new Pdfcrowd("apiname", "apikay");
// converted php file and store the generated PDF inside uploads
$fd = fopen( ABSPATH . 'wp-content/uploads/invoice.pdf', 'wb');
$client->convertFile( ABSPATH . 'invoice_html.php', $fd );
fclose($fd);
// set HTTP response headers
header("Content-Type: application/pdf");
header("Cache-Control: max-age=0");
header("Accept-Ranges: none");
//header("Content-Disposition: attachment; filename=\"invoice.pdf\"");
//$to = $invoice_email;
$to = "moyen#gmail.com";
$subject = "Invoice for your online package.";
$message = "Message Body Invoice for your online package. Invoice for your online package. Invoice for your online package";
$headers = array('Content-Type: text/html; charset=UTF-8','From: My Site Name <uddin#gmail.com');
// take the file from the uploads folder
$attachments = array( ABSPATH . '/wp-content/uploads/invoice.pdf' );
// send the generated PDF
//echo $attachments;
$wp_mail = wp_mail( $to, $subject, $message, $headers, $attachments );
}
catch(PdfcrowdException $why)
{
echo "Pdfcrowd Error: " . $why;
}