Here’s a 512px x 512px App Icon Template for general use. I built it on this
template. I removed all the clutter surrounding it and kept it as a single file. Ideally you don’t want to have more than one image to edit.
Download Template PSD
To export for different devices, follow these specs outlined by Apple in their Human Interface Guidelines
Just go Save For Web & Devices
in Photoshop and resize the image before exporting. Simple!
|iPhone/iPod Touch Retina||114px