That's not possible as of now. I have filed a feedback for this: FB13840897 In my app I did adopt UISplitViewController to show a sidebar when the window is large enough or a tab bar in compact size classes. For that to work I had to do custom code to restore view hierarchies when switching size classes. Now, UITabBarController has this behavior for free, but I don’t want to adopt the new top tab bar in my app, because it breaks my layout and I just don’t like the look and feel of it. It would be great to have an option to hide the top tab bar, while keeping the sidebar visible and show the bottom tab bar when switching to compact size class.

Has anyone tried with the latest iOS 17.2 beta? At first glance it's fixed as of iOS 17.2 beta 2, at least it does not crash any more with non-optional properties as it does on iOS 17.1 and below. I also don't see any attempts to sync in the console. So it seems like I can finally start bringing my app to SwiftData.

A context will save automatically periodically and on certain system events like didEnterBackground. If you want to save in the moment, you need to call context.save(). It might be possible that the autosave feature is buggy in Seed 1. The UI should update even if you don't manually save though.

An engineer answered this in the WWDC Slack. SwiftData does currently not support child contexts. A way around this would be to use a custom context, do the edits there and then apply them back to the mainContext and save it.