How to buffer PDF pages on CALayers in iPhone

Question

I am working on a PDFReader application.I am making use of CALayer to render the pdf contents.currently one pdf page is being rendered at a time and is displayed on the visible view.I want to buffer few pages(say one previous page and one next page for example) in advance while the user is reading the current page.Can any one please suggest me a better way of achieving this buffering mechanism?Thanks in advance