Updating macOS Icons

macOS icons are stored as icns files that contain the same logo in multiple different sizes and DPIs. Apple’s Human Interface Guidelines should be consulted for the specifics.

Although it may seem like we can simply be handed the highest resolution/DPI version and downscale for the remainder – this is not the case, some finer details in the icons (most notably shadows) need to be tweaked for each size. The UX team should hand off PNGs for every size and DPI needed.

Once those are in hand, the icns file can be created with something like the following:

mkdir firefox.iconset
mv icon_16x16.png firefox.iconset
mv icon_32x32.png firefox.iconset
mv icon_32x32@2x.png firefox.iconset
mv icon_64x64@2x.png firefox.iconset
mv icon_128x128.png firefox.iconset
mv icon_256x256 firefox.iconset
mv icon_256x256@2x.png firefox.iconset
mv icon_512x512.png firefox.iconset
mv icon_512x512@2x.png firefox.iconset
mv icon_1024x1024@2x.png firefox.iconset
iconutil -c icns firefox.iconset

(The NxN part is obviously the resolution, and the @2x string is used in the high DPI versions.)

This will create a firefox.icns file. You can verify that it includes all of the necessary resolutions and DPIs by inspecting it with Preview.app. You will likely need to do this for all brandings (official, aurora, nightly, and unofficial at the time of writing).