PDFs with multiple layers and iOS' CGPDF* library

H开发者_JS百科as anyone here had experience with rendering PDFs with multiple layers in iOS using CGPDF* (i.e., native API)? Can you please share your experience? Did you run into performance problems?

PDF layers are called optional content in PDF specification. They are implemented on top of standard page content, begin/end layer tags are used to mark parts of page content as part of the layer. The iOS CGPDF API ignores the layer tags and displays the entire page content. Because of this there is no performance difference between a PDF file with layers and one without.