below is the code snippet of the visualoforce email template.
<messaging:emailTemplate>
<messaging:attachment renderAs="PDF" filename="yourCases.pdf">
<html>
<body>
This pdf data I want in the apex as attachment to store.
</body>
</html>
</messaging:attachment>
</messaging:emailTemplate>
I Want this pdf attachmet in apex which I want to store as attachment on one object.