This script places a watermark image on top of the icons for your iOS app by going through each file inside an appiconset folder and rendering the watermark on top of your image. Tested on XCode 7, OSX 10.11 El Capitan
Install the two dependencies, ImageMagick and Ghostscript.
$ brew install imagemagick
$ brew install ghostscript sh tag_icons.sh tag YourProject/Images.xcassets/AppIcons/YourSchema.appiconset/
