I know that many icon templates already exist out there, but I wanted something simple and clean, and a PSD using Photoshop's Generator feature.
With this PSD, you'll be able to automatically generate an assets folder, containing all your image files (in retina and non-retina), named in a proper way to be used directly with Xcode or on your website/webapp.
Don't hesitate to ping me on Twitter if you have any question...
Licence : Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0)