Add the value to a PList
- Create an icon .icns resource file
- Edit the Info.plist file and change the "CFBundleIconFile" value string to "icon"
I use http://www.img2icnsapp.com/ to make an .icns from an image
Checkout the following instructions (link):
Use iconutil to Create an icns File Manually
The iconutil command-line tool converts iconset folders to deployment-ready, high-resolution icns files. (You can find complete documentation for this tool by entering man iconutil in Terminal.) Using this tool also compresses the resulting icns file, so there is no need for you to perform additional compression.
To convert a set of icons to an icns file
Enter this command into the Terminal window:
iconutil -c icns <iconset filename>
where <iconset filename> is the path to the folder containing the set of icons you want to convert to icns. The output is written to the same location as the iconset file, unless you specify an output file as shown:
iconutil -c icns -o <icon filename> <iconset filename>
Add the .iconset folder with the following 10 items:
icon_16x16.png icon_16x16@2x.png icon_32x32.png icon_32x32@2x.png icon_128x128.png icon_128x128@2x.png icon_256x256.png icon_256x256@2x.png icon_512x512.png icon_512x512@2x.png
I also use a great utility (http://makeappicon.com/) to create iOS icons with all the correct sizes.
They've added watch support so I've suggested Mac sizes too.
(It already has Android)
