App icon

The icon is an Icon Composer file in git: Icon/AppIcon.icon, a folder with icon.json and SVG layers in Assets/. You write both by hand. macOS adds the glass, the highlights, the shadow, the mask, and the dark, tinted, and clear looks. You never draw those yourself.

• tools/make_icon.sh compiles it with actool into Resources/Assets.car and Resources/AppIcon.icns. build.sh runs it when the icon changed.
• tools/icon_review.sh renders it with ictool (Icon Composer's command line tool, inside Xcode) into one contact sheet you read.

Older app without these files: copy Icon/, tools/make_icon.sh, tools/icon_review.sh, and tools/icon_sheet.swift from the new-mac-app template, the icon block of its build.sh, and CFBundleIconName = AppIcon from its Info.plist.in.

Other cases: more-cases.md.

• An Xcode or XcodeGen project (Xcode compiles the .icon itself).
• Converting an existing flat icon into layers.
• A Dock icon that changes with a theme or style. NSApp.applicationIconImage shows a flat picture, so render glass versions ahead of time.

The file

Icon/AppIcon.icon/
  icon.json
  Assets/front.svg     1024 x 1024 canvas, same as the icon
  Assets/back.svg

{
  "fill" : { "automatic-gradient" : "srgb:0.20000,0.42000,0.96000,1.00000" },
  "groups" : [
    {
      "layers" : [
        { "glass" : true, "image-name" : "front.svg", "name" : "front" },
        { "glass" : true, "image-name" : "back.svg", "name" : "back", "opacity" : 0.6 }
      ],
      "shadow" : { "kind" : "neutral", "opacity" : 0.5 },
      "translucency" : { "enabled" : true, "value" : 0.5 }
    }
  ],
  "supported-platforms" : { "squares" : [ "macOS" ] }
}