macadmin.fraserhess.com

This post assumes a familiarity with macOS packaging.

Apple’s aerial screen savers are a headlining feature in macOS Sonoma¹. These screen savers are also integrated with the desktop wallpaper, slowly pausing behind windows after the Mac is awoken or unlocked from screen saver. A screen saver/wallpaper combination featuring the Sonoma region of California is the default in macOS Sonoma. Apple further promotes this new feature directly to users who upgrade from macOS Ventura or earlier. They are encouraged to switch from their existing wallpaper to the new Sonoma flyover.

While this behavior boosts the visibility of the new screen savers feature and ties in with the Sonoma brand, desktop wallpaper is traditionally an area in which users express themselves with family photos or art. Also, organizations use the wallpaper to brand their computers or even communicate messages.

In macOS Sonoma, organizations can still enforce a desktop wallpaper with the same configuration profile as macOS Ventura: using override-picture-path in the Desktop payload. If an organizational admin wishes to set a default wallpaper that the end user can change—branding with a lighter touch—the solution is less obvious.

There are three components to setting a default wallpaper:

1. The branded wallpaper must be available locally
2. A default configuration must be created
3. A preference is set telling macOS that the wallpaper is configured

Branded wallpaper file

Either by script or by package, the branded wallpaper image file must be installed locally. It should be writable only by root and readable by the world (Unix permission 644). In the demo files I include later, the wallpaper is installed to /Library/Application Support/com.fraserhess.macadmin.

Creating a default configuration

Configuration for the wallpaper/screen saver system is stored in a new location in macOS Sonoma:
~/Library/Application Support/com.apple.wallpaper/Store/Index.plist

To create a clean version of this configuration, first install a fresh macOS Sonoma on a Mac with a single monitor, preferably a MacBook. Do not create additional spaces. Install the branded wallpaper in the desired location. Open System Settings and find the Wallpaper pane. Drag the branded wallpaper file to the image well at the top of pane. Make sure it comes from the same file path as it will be installed to later on all of your new Macs.

In the Screen Saver pane, make any changes you desire to pick a default screen saver. (I still use the Message screen saver by default.)

Close System Settings. Now one can copy the Index.plist from the path above. To have this installed for every new user account, install it in the default User Template. See the next section for the final layout of these files in a package.

Required Preference

A preference must be set that to tell macOS that wallpaper is configured and to not attempt a migration from the previous store. If it is not set macOS will still prompt the user to choose between the branded wallpaper and the Sonoma default.

In the com.apple.wallpaper domain set the SonomaFirstRunMigrationPerformed key to true.

This can be done with Managed Preferences but that approach should be used sparingly. Setting SonomaFirstRunMigrationPerformed on a Mac that is upgrading from macOS Ventura will not prompt the user to switch to the Sonoma default wallpaper, but rather just use the Sonoma default wallpaper.

Alternatively, a com.apple.wallpaper.plist file can be added to the User Template. Here is the final layout of the package:

These demo files are available for download and include an unsigned demo package.

I hope this helps with branding your Macs on macOS Sonoma.

1. As I write, the new screen savers are literally the first feature highlighted on https://www.apple.com/macos/sonoma/ ↩︎