There are two options,
1. Put the PDF Virtual Device on the printer. This allows you to send PDFs directly to the printer as files which will be handled and printed within the printer. It does costs money to add this feature.
2. Convert the PDF to an image in your app. With iOS this is easy as it has a built in PDF rendering engine. Re: Generate PDF Document from android/iOs using Zebra iMZ320 spool. With Android, you need a PDF renderer to convert it. Unfortunately I can't recommend any at this time. The free ones we've looked at are fairly bad and the decent ones we looked at are expensive.
Any thoughts from the community on decent Android PDF tools would be appreciated.