Add a signature image to a pdf in iOS for the iPhone/iPad in particular

With the iOS support for Quartz 2D and its support for the PDF format; should adding a signature image to a pdf be a little easier. I have looked all over and saw people are using the PDFKit, UIView or Core Graphic Library. Which is the easiest and the recommended library for the effort? Also, are there simple examples of the recommend library. When I tried to see how Quartz 2D worked, all I could find are narrati开发者_StackOverflowve explanations about how it worked and specific method you may use but no complete examples. You know the hello world one. Anyway, I am new to iOS development but been writing code for over 20 years so I might be able to pick this OS up as well.

Can some poor soul have pity on me and please point me in the right direction?

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I have done this by loading the old pdf file on view and then add signature on that view and then render the view. check the following post

Add a signature image to a pdf without showing the pdf data to user in iOS

But not able create the pdf which contain existing pdf with signature "without showing on view" .

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It's too late to answer this question now. But let me just provide some pointers for people who may bump into this question in future.
This one summarizes PDF handling in iOS pretty well. Good for starters. http://www.ioslearner.com/generate-pdf-programmatically-iphoneipad/#more-242
This one is also similar, but not very exhaustive. http://www.absoluteripple.com/1/post/2012/03/generating-pdf-in-ios.html
The above links do not talk about handling existing PDFs. I found this stackoverflow answer really useful for that. Add pdf page to an existing pdf objective-c Just a note, if you want manipulate existing PDFs, Quartz 2d is the way to go.
Also look at reference pages of CGPDFDocument, CGPDFPage, CGPDFContext and CGContext.