Bitrig can now build native apps for Apple’s folding iPhone Duo and test them in an interactive 3D simulator. The update gives developers a way to explore the phone’s hinge, two displays, and changing poses before the hardware reaches customers.
Bitrig announced the new support on September 18. Its simulator lets a developer grab the virtual phone, fold or rotate it, and watch a SwiftUI app respond in open, closed, tent, and laptop-like positions. The company says standard navigation and controls already handle part of the adaptation.
A simulator built around the hinge
Developers can use Apple’s onHingeChange API to react as the fold angle changes. ArrangementView can place media on the upper half and controls below when the phone rests on a table, while CameraCaptureAccessory can put useful information on the outer screen for the person facing the camera.
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The release addresses the hands-on testing gap described in our coverage of Apple’s iPhone Duo developer tools. Videos and interface guidance can explain adaptive layouts, but an interactive device model shows whether an actual app resizes cleanly and responds correctly to a fold.
Bitrig requires the Xcode 27.1 beta and iOS 27.1 simulator for this workflow. That is separate from Apple’s broader April 2027 App Store SDK requirement, which does not by itself require an app to adopt Duo-specific layouts.
Bitrig builds native SwiftUI projects rather than a separate runtime, so developers can continue working with Apple’s frameworks and tools. It can also help update an existing app using Apple’s App Resizability guidance.
iPhone Duo is scheduled to reach customers on October 23. Bitrig’s simulator will not replace testing on the final device, but it gives small teams an earlier way to find layout, orientation, and hinge-state problems before launch.
The company is also hosting a September 26 iPhone Duo hack event in San Francisco for developers exploring the new form factor.
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