title: Draw content on existing PDF Document in specific Page
body: <p>So I am implementing a specific type of PDF editor for the iPad, for personal use.
  I have already implemented the PDF viewer, and now i am stuck in the editing part. Here is the deal:
  I display each page of the document in a UIView, and then create another view, with the exact same size of the page inside it. I then let the user draw on the view</p>
  
  <p>Now, say i want to print that UIVIiew in the exact page of the PDF file it was drawn.
  I am aware of a way to do this, but it is taking too long for bigger documents.
  I was doing it like this (simplified the code for better understanding):</p>
  
  <pre><code>UIGraphicsBeginPDFContextToFile(file, pageSize, nil);
  
  for (size_t currentPage = 1; currentPage &lt;= pageCount; currentPage++) {
  
      UIGraphicsBeginPDFPageWithInfo(pageSize, nil);
      CGContextRef ctx = UIGraphicsGetCurrentContext();
      //translates context, copies doc page to the new pdf, translates back
      CGContextTranslateCTM(ctx, 0, pageSize.size.height);
      CGContextScaleCTM(ctx, 1.0, -1.0); 
      CGPDFPageRef page = CGPDFDocumentGetPage (document, currentPage);
      CGContextDrawPDFPage (ctx, page);
      CGContextScaleCTM(ctx, 1.0, -1.0);
      CGContextTranslateCTM(ctx, 0, -pageSize.size.height);
      //custom drawing goes here
      if(currentPage == desiredPage) [imageFromView drawInRect:pageSize];
  }
  UIGraphicsEndPDFContext();
  </code></pre>
  
  <p>The problem here is that this procedure recreates the entire PDF, and for larger documents, this can take minutes to finish.</p>
  
  <p>I needed a solution that prints the UIView (that the user drew on) in a page of the PDF document, without having to recreate the whole document.</p>
  
  <p>Any links, tips and other useful information are very appreciated. Thanks in advance</p>