Annotation of a PDF file in my Dropbox in iPad and keep it the last version in Dropbox

I have a folder in my Dropbox that I keep my eBooks in it. I want to find an app for the iPad that can do these to me:

• Let me open a PDFs file from my Dropbox
• Let me annotate on that file
• Annotation getting applied to the Dropbox version of my file, instead of creating a local copy that its changes does not affect the Dropbox version

In my PC, when I open a PDFs file from my Dropbox and make Some highlights, when I press the save button in acrobat reader, the Dropbox version is instantly gets updated and whenever I open my Dropbox folder I have the latest version of the file. I need similar functionality in my iPad.

What iPad app has this functionality?

Solution 1:

A few days ago Dropbox introduced a collaboration with Adobe that allows to annotate files and synchronise changes back to Dropbox automatically:

With the latest versions of the Dropbox and Acrobat Reader iOS apps, you’ll be able to annotate and comment on PDFs stored in Dropbox, right from your iPhone or iPad. Just open a PDF from the Dropbox app and tap the ‘Edit’ icon, then edit or electronically sign the PDF in the Acrobat Reader app. All your changes will save back to Dropbox, so you and any collaborators will have the latest version.

[...]

To try out the Adobe integration on your iPhone or iPad, download the latest versions of the Dropbox iOS app and the Acrobat Reader iOS app. The same integration will be available for Android devices next year, so stay tuned!

Solution 2:

I am using PDF Expert for exactly this. You can choose to sync folders from Dropbox (and other sharing services). Those folders will keep a local copy and will automatically sync back as well.

Solution 3:

PDF Max Pro does that:

SEAMLESS iCLOUD & DROPBOX INTEGRATION:
Work on your PDF documents stored on iCloud or Dropbox just like your local files. Search or browse any file you need, annotate or fill in, then all your changes are automatically pushed back to the cloud without any manual step required.