title: Edit PDF in iphone application
body: <p>Now I am creating an application that works like '<strong>iAnnotate PDF</strong>' 
  Till now I have completed reading and displaying pdf pages in UIView. 
  Even I am sucessful in getting TOC. </p>
  
  <p>Now I want to edit PDFs, Editing includes marker, highlights and writing notes.</p>
  
  <p>Now my question is how to edit? I mean do we need to create another pdf and over write it with new changes? </p>
  
  <p>Or there is any way we can update single page in existing pdfs??
  If yes how is that done?</p>
  
  <p>If we are rewriting the entire pdf, wont that be creating overhead?</p>