How to print pdf on wi-fi printer?

Apple does not make printers, so there is no such thing as a non-apple printer. iOS supports air print to wifi printers that support that feature. A list of all compatible air print printers is here - About AirPrint - Apple Support If your wifi printer supports air print, then just open the PDFs in iBooks or your favorite PDFs app, select the box with an arrow in it from the upper right corner and select print.