seeing as though your solution is going to a mobile platform, your pdf file would be stored in the filemaker file itself... so, what you would do here is to export the field contents to the temp directory...
select open automatically on the export field contents export option. (or email if you want to email it)
When using the description as the filename, it's important to note that the description must comply with the OS filename restrictions (no funny characters that might stuff up your directory path, you may even find some custom functions out there that strip out all the nasty characters before it exports, so there will be no issues.
If all you want to do is read/view the PDF, don't forget that it is possible to do this in the container field itself. All you need is an instance of the container field, which can be on a separate layout, that is optimised for interactive content and large enough to make the content readable. You could make it dynamically resize according to the screen size if you want to.
If the OP wants to use this on an iPad, interactive containers do not work. If the PDF is one page you will be able to view the PDF in a container whether it is set to image or interactive. If the PDF is multiple pages you will not be able to view it in the container.
Ahh! I didn't know that. Not fully FMGo literate.