FoldWall

FoldWall is a wallpaper previewer and cropper for iPhone Duo. One wallpaper has to cover two screens, and until you actually set it there's no way to tell what either screen will get.

FoldWall shows both at once. Drag or pinch your photo and the closed-screen and open-screen framings update side by side, so you can see how each one lands before you save anything.

How it works
1. Pick one photo from your library.
2. Drag or pinch on either preview. Both framings update together.
3. Unfold the device to check the inner screen at full size.
4. Save, then set it from Settings ▸ Wallpaper.

Why one photo covers two screens
The cover screen shows almost exactly the middle vertical slice of the inner screen. You only ever set one wallpaper, and iPhone Duo takes from it whatever the active screen needs. That's why the framing matters, and why seeing both at the same time is the whole point.

Unfold for a real check
Open the device and FoldWall drops its interface, drawing your wallpaper edge to edge on the inner screen. Not a mockup, not an animation — the finished image, on the screen it was made for. Fold it closed and you're back to adjusting.

Framed to the actual hardware
Both previews use the device's real pixel dimensions and real corner radii, down to the cover screen's uneven corners: 8 pt on the hinge side, 59 pt on the other. Those numbers come from the device profile, so the preview is worth trusting.

Entirely on your device
No account. No network requests. No analytics. No tracking. No data collection. No subscriptions and no in-app purchases. Photo access is add-only, so FoldWall can save the wallpaper it makes and nothing else.

Good to know
• iOS gives apps no public way to set wallpaper, so the last step happens in Settings rather than here. It's the only route the system allows.
• The smallest zoom still fills both screens, so an empty edge isn't possible.
• Reset returns the photo to centered and filling both screens.
• A first-run guide covers the five things you'd otherwise have to work out yourself, and stays available under Settings ▸ How It Works.