As it's not one of the HP printers that support AirPrint, you will need an app in order to print to it. I don't think that Canon have their own app, but there are a number of third-party print apps e.g. Print n Share, PrintCentral etc.
I have a Canon MX6150 as well. I downloaded the free Canon Easy-PhotoPrint app from the App Store. Then to print, select "open in" > select iEPP > select papersize > select plain paper > select print. Succes.