Neither vendor has shipped iPhone Duo support or published guidance, as of 9 September 2026.
Both will still work. React Native’s flexbox layout and Flutter’s constraint-based layout both adapt when the native view is resized, so an app built without fixed pixel values reflows correctly.
What neither can reach today is the fold-aware API surface — reserved regions, arrangements, hinge angle, scene accessories and the vertical bar APIs have no JavaScript or Dart bindings. Getting at them requires a native module or platform channel.
Full analysis for each: React Native on iPhone Duo and Flutter on iPhone Duo.
Flutter is closest to ready in principle, because MediaQuery.displayFeatures already models hinges and cutouts for Android foldables. Whether the iOS embedder populates it for iPhone Duo is unconfirmed — assume it is empty and verify on a real build.
What is actually reachable
Both frameworks lay out correctly, because their layout systems resize with the native view. What neither can reach from JavaScript or Dart today:
ReservedRegion— where the hinge divides the displayArrangementView— pose-aware primary/secondary placement- Hinge angle, scene accessories, the vertical bar APIs
Getting at those needs a native module or platform channel. For most content apps that is unnecessary — correct layout is the whole job. For a canvas, editor or game board where the fold matters, budget for native work.