Load auto paged pdf in iOS like iBook

Question

In iBook, when you open a PDF, you can auto format and paged the pdf, e.g. if in iPhone, there are 5 pages, but when you view with iPad, it only contains 2 pages.

When you change the text size, the page also updated automatically.

How to do this using CGPDFDocumentRef?

Answer 1

I'm assuming you are talking about Apple iBooks on the iPad? Are you sure you are observing the behavior of a PDF and not an ePub file?

The native format of iBooks is either ePub or the format created by iBooks Author.

PDF files are usually (in the vast majority of cases) used in a non-reflowing way. Reproducing the exact visual appearance of pages - explicitly without reflow - is exactly why PDF was invented.

There are constructs you can add to PDF files to make them a little more alike to formats like HTML and ePub; these constructs can tag text with styles, logically define paragraphs, columns and tables and so on. Usually they are used to make a PDF file suitable for long-time archiving (according to the ISO PDF/A standard) or accessible (suitable for reading by screen-reader software for vision-impaired people for example). Such a PDF file is commonly referred to as a tagged PDF.

As far as I know iBooks doesn't actually support tagged PDFs (meaning, it doesn't use the information in such a PDF file to reflow the file). And as far as I know you cannot create the necessary tags and structure with the built-in iOS library.

If your target app is iBooks, you'd probably be better off looking into generating ePub...