macOS Tahoe’s New Theming System
In System Settings ➝ Appearance, there are still the standard Auto, Light, and Dark modes, but Apple has added several options that allow you to really mix things up and create your own stylized desktop environment.
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Meanwhile, a new “Icon & widget style” section offers three distinct modes alongside the Default. Like iOS 18, the new Dark option applies black backgrounds to icons throughout the system interface, including System Settings sidebar icons (this works in both Light and Dark modes). You can set this to Always or Automatic, which switches to dark icons at night while maintaining the default appearance during daylight hours.
The new Clear setting emphasizes the Liquid Glass redesign and adds a new transparency by picking up background colors, creating a more translucent interface effect. Clear also includes Light and Dark variants, or it can be set to Auto for automatic day-night switching.
You use your favorite design tool to craft the individual foreground layers of your app icon. For iOS, iPadOS, macOS, and watchOS icons, you then import your icon layers into Icon Composer, a design tool included with Xcode and available from the Apple Developer website. In Icon Composer, you define the background layer for your icon, adjust your foreground layer placement, apply visual effects like transparency, define default, dark, clear, and tinted appearance variants, and export your icon for use in Xcode. For additional guidance, see Creating your app icon using Icon Composer.
The system renders your app icon for the different platforms, appearances, and sizes from the single Icon Composer file located in your app’s bundle. For previous releases that don’t have the same icon and widget style appearances and Liquid Glass material, Xcode generates the app icon images at build time from the Icon Composer file.
If you choose not to use Icon Composer, you can still use an AppIcon asset catalog in your project containing individual app icon images and let the system apply the Liquid Glass material.
I think I read that you still need the old icon file, anyway, since the new .icon file only deploys back to macOS Sequoia.
Create icons with Icon Composer:
Learn how to use Icon Composer to make updated app icons for iOS, iPadOS, macOS, and watchOS. Find out how to export assets from your design tool of choice, add them to Icon Composer, apply real-time glass properties and other effects, and preview and adjust for different platforms and appearance modes.
Now, with the newest version of its platforms (26) being announced, new appearance modes were introduced alongside the new unified design language, Liquid Glass. There are now multiple ways an app icon can be rendered, depending on the user’s system appearance settings and how it interacts with the background content. They are Default, Dark, Clear Light, Clear Dark, Tinted Light and Tinted Dark.
macOS 26 Tahoe replaces the oddly shaped app icons that once brought joy and personality to the Dock with the familiar squircle icons from iOS.
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When you manually assign an app icon through Finder, macOS respects the shape and doesn’t force the glass background. Interestingly, this also works if you just replace the icon with the same one.
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Although squircle icons are now the default, developers can still display a custom-shaped icon in the Dock by setting a view on
NSApplication.shared.dockTile.contentView.
People are using this to get their Dock icon out of “squircle jail” if they haven’t updated it yet. But I don’t understand what you’re supposed to do if you want to programmatically set your Dock icon (e.g. to draw a custom badge on top) but you do want to adapt it for the different appearance settings. If I set the applicationIconImage, it seems like macOS displays exactly what I gave it (which makes sense). But does that mean that you have to handle drawing all the different theme combinations yourself?
Previously:
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Hey Michael - do you recall where you read that you still need old icons to support pre-Sequoia? I've been mucking around with Icon Composer and the Xcode 26 beta this afternoon and haven't found the right combination of files to make icons appear correctly on different versions of macOS.
Thanks
- Jon
@Jon I think it was on Mastodon or Twitter, but I can’t seem to find the link. IIRC, you want the old icon file to still be there under the same name (but different extension). I haven’t had a chance to test this yet.
> People are using this to get their Dock icon out of “squircle jail” if they haven’t updated it yet.
But what about the Finder?
If Tahoe's theming options can't do things like this: https://macthemes.garden/
...then what good is it?!
