This post is from the Activity iPhone Duo UIKit Q&A.
On unfolding, our app's horizontalSizeClass becomes .regular, and UITabBarController automatically promotes to the iPadOS-style sidebar. We suppress this with mode = .tabBar (iOS 18+) and sidebar.preferredPlacement = .tabBar / sidebar.preferredLayout = .tile (iOS 27+) to keep a bottom tab bar. Is this the correct/recommended approach for a foldable iPhone's inner display, or is there a foldable-specific tab bar mode we should be using instead?