Wishlist item: index and search pdf-files

From the Relevanssi feature page :

Features Relevanssi doesn’t have

As great as Relevanssi is, there are some things it doesn’t do. Here’s a quick list of the features people most often ask for but which Relevanssi doesn’t offer.

Relevanssi can’t search the contents of PDFs, Word documents, Excel spreadsheets or other external files.

Correct. Reading PDF file contents isn’t particularly simply. With that code of yours it might be possible for PDFs stored as WP attachments (so any hits to the PDF could lead to the attachment page). I’ll have to investigate this, but no promises.