Xcode 27.1 includes an iPhone Duo simulator, which runs inside Device Hub. Apple’s Tech Talks describe on-screen controls to open, close, rotate and fold the simulated device, so you can check the layout in every pose.
Apple released Xcode 27.1 beta on 18 September 2026. It needs macOS Tahoe 26.6 or later, and its known issues matter here: most app extensions and StandBy cannot be tested in the iPhone Duo simulator yet, so those wait for a real device.
Test the transitions, not just the end states — most layout bugs appear while the device is folding rather than once it has settled.
For automated coverage, snapshot tests at the two display sizes catch regressions cheaply: 626 × 890 points for the inner display and 466 × 678 for the outer. Those will not exercise the hinge division regions, so keep a manual pass for the partially folded poses.
A pose matrix worth running
Poses multiply with orientation and multitasking, so test deliberately rather than by exploration:
| State | What to check |
|---|---|
| Closed | Compact-width layout; toolbars and tab bars at the side |
| Open flat, portrait | Regular width, sidebar should appear; bars horizontal |
| Open flat, landscape | Bars back at the side |
| Partially folded | Division region active; nothing across the fold |
| Split View, various widths | Continuous reflow across the divider’s range |
The transitions matter as much as the states — most bugs surface while folding, not after.