I think he is looking for an app which let you make annotations and write/type directly onto and within the PDF document...
There are no such app at this time for this purpose.
There is. '
Annotater,' [sic]. I find it grotesquely hackish and in fact was coming onto the forum just now to look for an alternative to it.
It has a Mac-only syncing program that syncs folders of pdfs, which is a lot less useful than it sounds, because for example, I use
Papers so I can either choose to share my entire collection, or let Papers manage by author name, then sync each author separately. It turns out that one cant just sync everything shared on the computer, but instead needs to sync each folder (i.e. for me, author) separately. Furthermore, there are glaring oversights such as the syncing failing when the iPhone falls asleep, so you have to supervise your iPhone while syncing (which is an interactive process anyway by the aforementioned problem).
There's also no way, as far as I can tell, to set Annotater as a opening app for pdf filetypes (with an advanced settings app), which would be very useful, for example, when my class notes are emailed to me in PDF.