I’m curious about the same thing. Is there no costs now? And is that sustainable or will it kick in at some point?

Ok so you can use those delegate methods to know when the transition is about to happen and then set your TabBarController or SplitViewController accordingly... ...and you say not to reparent views from your TabBarController to SplitViewController (and visa versa) ...but how exactly to you then restore your position in the hierarchy? In the WWDC20 Build for iPad video @19:42... she mentioned something about the "Restorable" protocol? Is this a protocol we make ourselves or is this part of UIKit? I couldn't find any mention of it. Thanks, Kevin