For some reason the iPad safari browser does not handle embedded PDFs well. PDFs view fine on their own when launched standalone, but not with the object tag. The problem is t
PDF.js can be the right choice. It works perfectly for us.
You just download it from https://mozilla.github.io/pdf.js/ and place it in your website.
Then it can be included in an iframe
A demo can be found here: https://mozilla.github.io/pdf.js/web/viewer.html
Regards