Bitrig has added support for building and testing iPhone Duo apps, complete with an interactive 3D simulator that lets developers fold, tilt, rotate, and position the device however they want. The update landed last Friday, days after Apple opened the door to iPhone Duo development itself.
That door opened with Xcode 27.1 beta 1, which gave developers Apple’s own tools for building and testing iPhone Duo apps for the first time. Bitrig’s take adds a more hands-on simulator on top of what Apple shipped.
Bitrig Started as a Vibe-Coding App and Grew Into a Full Xcode Companion
Bitrig launched as a simple vibe-coding app that turned text or voice prompts into native SwiftUI apps running right inside the main Bitrig app on iPhone. Since then, the platform added a Mac app with access to the full Xcode toolchain, an integrated iPhone simulator, on-device testing, and the ability to export finished projects to Xcode or ship them through TestFlight and the App Store.
The new iPhone Duo simulator builds on that foundation, and it goes further than a static preview. Kyle Macomber, Bitrig’s co-founder and CEO, laid out what the update actually lets developers do:
- Every pose: Drag, fold, and rotate the 3D model to preview how an app looks folded flat, standing like a tent, or lying like a laptop, in both portrait and landscape.
- Hinge-aware effects: Read live hinge angle data inside the simulator and use it to drive interface changes as the phone opens and closes, similar to Apple’s own unfold animation.
- Table-mode layouts: Arrange media on the upper half and controls on the lower half for when iPhone Duo is propped up like a tent, with support for using the outer display in landscape.
- Dual-display camera use: Show something useful on the outer display, like a live preview, for whoever is facing the camera while the app runs.
Macomber also said Bitrig helps developers manage multiple versions of Xcode at once, so they can start building for iPhone Duo on the beta while still shipping regular updates through the stable release of Xcode 27.
Developers Can Try the Simulator Without Owning an iPhone Duo
iPhone Duo doesn’t ship until next month, and access to a real unit before then is limited to Apple and its partners. A 3D simulator that responds to fold angle and orientation gives outside developers a way to start shaping how their apps handle the second screen months before any of them can test on real hardware.
Bitrig detailed the update in a blog post, including the technical specifics on how the hinge and dual-display APIs work inside the simulator.
