All my iPad drawings have been produced using an iPad Pro and a stylus and printed. The drawings usually start with a basic rubber tipped stylus or a finger and then for more sensitive and precise marks I use an iPencil. All drawings are made from direct observation initially. In some cases the drawing may have been subsequently manipulated. I've been working with the iPad since July 2012. My book 'Life Drawing on the iPad' has just been published by Crowood Press. It is a guide to drawing and painting from the figure using the iPad. Check your local bookshop or order on-line from Amazon etc.