How to Draw in existing PDF?

I have a pdf document which has some dat开发者_如何学运维a stored in it. I want to write some more data to same file. I think it will be possible by Quartz 2D programming using transperancy layers. But i am not able to get how to do it. (My pdf is stored in documents folder of iphone application).

Please Help..

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2D programming provides many api to handle a PDF File. Basic strategy can be to draw PDF on context and then edit that context the way you want and then save it.

you can find some details here.

http://developer.apple.com/library/mac/#documentation/GraphicsImaging/Conceptual/drawingwithquartz2d/dq_pdf/dq_pdf.html#//apple_ref/doc/uid/TP30001066-CH214-CJBHHJCB

Above also include some sample code.