[Feature Request] Support Liquid Glass Icons for macOS 26

[iamEvanYT]

Behaviors

Current (macOS 15)

To add an icon to a macOS app, all you have to do is to create an .icns file and stuff it in the app's Resources folder.

You can provide the .icns file to electron-builder, and it will automatically bundle and make it work with the app.

Soon (macOS 26)

Apple introduced a new way to create icons using Icon Composer. This is not a standard image format and has assets & layers bundled inside it.

However, this app creates .icon files which does not currently work with electron-builder.

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Feature Request

Make .icon files work automatically with electron-builder. Provide it via electron-builder config, and automatically bundle it into the app.

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Current Workaround

This method is a workaround for the issue, and can be used for electron-builder to automate this process.

1. Create a Xcode project for a macOS app with the .icon file configured as the app icon.
2. Extract the Assets.car from the app's Resources folder which contains the bundled app icons.
3. Create a custom afterPack hook which copies the Assets.car into the app's Resources folder.
4. Extend the Info.plist with a CFBundleIconName key, which point towards the App Icon inside the Assets.car. This is demonstrated below.

electron-builder.json:

{
  "mac": {
    "extendInfo": {
      "CFBundleIconName": "AppIcon"
    }
  }
}

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I have a sample of the workaround, which is implemented here.

[mmaietta]

Where does the .icon file go? Happy to look into this since we're just accepting a new file type (and not doing any command line format conversions or creation). Does CFBundleIconName act as a path?
I see this https://developer.apple.com/documentation/bundleresources/information-property-list/cfbundleiconfile but not sure how it works.

Any chance you could provide me a .icon file or (even better) a sample repo for me to debug with?

[iamEvanYT]

Happy to look into this since we're just accepting a new file type (and not doing any command line format conversions or creation).

Unfortunately, this definitely requires some level of interaction with Xcode or its CLIs. The .icon file (which is secretly a folder, like .app) is placed inside the Navigator in the Xcode Project, and defined in the app settings. (Screenshot below) Then when Xcode builds the app, it automatically bundles the icon into a Assets.car file.

Does CFBundleIconName act as a path?

It takes the asset name to find it inside the Assets.car. The image attached below is what I added in electron-builder.json
to make it work.

[quinton-ashley]

Anyway we could replicate what Xcode does to make the Assets.car file?

Also can it be added after the build is complete?

[iamEvanYT]

Anyway we could replicate what Xcode does to make the Assets.car file?

Not with what I know so far.

Also can it be added after the build is complete?

Yep! You just have to move the Assets.car into the built app and add a key to the Info.plist of the app.

[quinton-ashley]

@iamEvanYT Well that's good! What's the key that needs to be added?

[iamEvanYT]

Well that's good! What's the key that needs to be added?

Basically, just add this to electron-builder's configuration. The value AppIcon should be replaced with the name for your .icon file.

[Kilian]

Packager has a solution that generates the assets.car file for you during build: https://github.com/electron/packager/pull/1806/files that's probably something that can be reused for builder.