It was during the event, they just displayed an overly dramatic LOC comparison on the screen between a few page-downs on a longer Swift file, then the next screen showed a ~10 line block of code which does the same thing. Followed by the standard audience applause.
The livestream hasn't been uploaded yet but I'm sure you could find it in one of the live blogs.
Part of that comparison (on the "before" side) was a bunch of Cocoa autolayout code. It's verbose and annoying, only mitigated if you're using Interface Builder, which has its own significant downsides. If the declarative form in SwiftUI supports a saner approach to managing and adjusting layout, then there's absolutely nothing overdramatic about that comparision. It's a potential game changer.
