An inspection app in the works whose touch test packs smaller cells along the crease
Does FoldCheck: Foldable Inspector work on iPhone Duo?
Seen in the simulator, but not out yet: the developer's screenshots show a home screen on the cover and a touch test with finer cells along the crease. It isn't on the App Store.
- Simulator verifiedJack Yu, the developer, in screenshots of a development build in the iPhone Duo simulator, published in the project's review gallery on GitHub apart from its older drawn mock-ups. The app isn't on the App Store.
Adapted for the fold
- Closed · Outer display
A stacked home
Closed, the cover stacks the button that starts an inspection above the last result and the quick test actions, with navigation down the side.
- Open · Inner display
Panels side by side, finer cells at the crease
Open, the start panel sits beside the last result and the quick actions. The touch test packs smaller cells into a band along the crease, upright and in landscape.
About FoldCheck: Foldable Inspector
FoldCheck is Jack Yu’s app for inspecting a phone step by step, and it isn’t out yet. On the cover its home screen is compact; open, the start panel moves beside your saved results and quick actions. The touch test uses smaller cells around the crease, and keeps each tested cell tied to the same spot on the glass when the screen rotates.
The screenshots come from the iPhone Duo simulator with sample data, and the hinge graph in them is a simulated sweep. Calibrating against a real hinge, touch scale, the camera and the other hardware checks are still to do.
The app can put together a report of the tests you’ve run yourself, though the developer’s notes say that isn’t a certificate from Apple or an insurer. It hasn’t reached the App Store yet.
Evidence reviews
What we checked, when, and what the evidence establishes. Each record preserves the support label at that check.
· Simulator screenshots reviewed
Simulator verified · iphone-duo
Looked at seven screenshots the developer published from the simulator: the cover's stacked home, the wider two-panel home open, light and dark versions, a mock hinge graph, and touch grids with a finer band along the crease, upright and in landscape (each with 3 of 512 cells marked).
Poses shown: Closed, Open. These are observations of the evidence, not a test of every interaction.
App version: Not recorded in this evidence. Environment: Xcode 27.1 RC (27A9275), iPhone Duo simulator on iOS 27.1, as the developer notes.
A development build with no version given, using made-up sample sessions and a simulated hinge sweep, as the developer notes. The screenshots show the phone closed and open flat, not half-folded or turning. No code was run and nothing was tested on hardware.
View reviewed evidence ↗
On the ideas wall
All ideasFoldCheck: a touch grid with a denser crease band
by Jack Yu
Jack Yu's inspection app, not out yet, stacks its test actions on the cover and sets them beside the start panel when open. Its touch test packs smaller cells into a band along the crease. Simulator screenshots, with sample data.
Related guides
The best iPhone Duo apps so far (October 2026)
The apps worth installing on day one, from Apple's four launch partners to indie apps whose developers have shown a real iPhone Duo layout, picked for what they do when you open the phone.
Do your apps work on iPhone Duo? What happens before they're updated
Every iPhone app opens on iPhone Duo, but only updated ones fill the inner display. What an app looks like before its developer adapts it, how to tell which are ready, and which popular apps have said so.
Is this your app?
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<a href="https://foldhunt.com/apps/foldcheck/"><img src="https://foldhunt.com/badges/featured-on-foldhunt.svg" alt="Featured on FoldHunt" width="220" height="54"></a>Need to update the listing? Email the editor.
Sources: FoldCheck's simulator screenshots (github.com) · FoldCheck: validation, and the device checks still to do (github.com) · FoldCheck: draft App Review notes and what it can't measure (github.com) · FoldCheck on GitHub (github.com)
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