iPhone的PDF查看/注释库？

I am currently working on an educational project where I would like to add some PDF reading functionality to an iPhone app. I know that it is possible to add a UIWebView and display the PDF there, however I would like to add the ability to show page number, 'next', 'previous' buttons etc. Is CGPDFDocument the direction that I should be headed or is there a better (ie more feature rich) library available? I have had a look around to try and find the capabilities of CGPDFDocument, but besides the API reference there is not much available. I am currently working on an educational projec