Same. A few months ago I pointed Opus 4.6 at a mid-size Vue app and told it to create the iOS equivalent using SwiftUI, and it nailed it. I broke the process down to phases and reviewed each phase, but within about ten days I had a functioning iOS app that had full feature parity.
I've done the same with DS-V4-Pro, GLM-5.2, MiMo-2.5-Pro, etc. - this is a task pretty much any agentic model can handle nowadays.
(I do the reverse currently where I implement a macOS front end natively, and then just let the agent rip on porting that to an HTTP API server + React/TypeScript/HTML/CSS frontend, because it's significantly easier to have agent loops fiddle with making macOS apps than it is to fiddle with a web browser and CSS.)
That's awesome! Did you follow any sort of framework in your phasing? We to migrate our entire app so any tips would be helpful.
UI: SwiftUI (primary), UIKit (limited), PhotosUI, WebKit, MapKit, Charts
Data/Concurrency: Foundation, Combine, Observation (@Observable)
Platform: CoreLocation, UniformTypeIdentifiers
Tests: Testing (Swift Testing)