Default paper size and unit for PDF documents on iOS

Question

For creating PDF documents in iOS, in the official documentation (http://developer.apple.com/library/ios/#documentation/2DDrawing/Conceptual/DrawingPrintingiOS/GeneratingPDF/Gen

Answer 1

PDF and PostScript use "PostScript points" as a unit. A PostScript point is 1/72 inch. So the default page size is

612 x 792 points = 8.5 x 11 inch = 215.9 mm x 279.4 mm

This is the US Letter paper size.

The bounds rectangle in UIGraphicsBeginPDFPageWithInfo() defines the so-called "media box" of the PDF page. The media box is the size of the medium on which the page should be printed and therefore includes the margins.