PSPDFKit is a heavily optimized framework for displaying PDF files with horizontal scrolling. It is fast, flexible, has intelligent caching and renders pages usually faster than iBooks.
Amazingly easy to use and impressive PDF performance - closest thing to iBooks so far. -- Martin Reichart, iOS Developer
You can purchase a license and the full source code at http://pspdfkit.com.
This is example code to show you the features of PSPDFKit. You need a license if you want to distribute this within your application, see License.md for details.
PSPDFKit uses 3rd-party code, see ACKNOWLEDGEMENTS for contributions.