The premiere of the iPhone Duo, subsequent generations of foldable models from Samsung and Xiaomi, and new Android Adaptive Quality guidelines mark a clear boundary in software design. The argument “we have a working app” is no longer enough. Foldable app development has stopped being a niche engineering experiment and has become a concrete product decision that lands in the backlogs of most teams.
For apps built before 2025, this means a specific architectural test. According to data from IDC and Counterpoint Research, the foldable screen market is growing by 30% year-over-year. User profile research shows a clear pattern: people choosing this type of phone are mainly wealthier clients, management staff, and so-called power users. This group uses multitasking 50% more often than the average user, gladly pays for digital services, and has the lowest tolerance for poor UX.
Four physical layouts, one device
Apple, Samsung, and Google now define four app operation states on a single device, confirmed in iOS SDK documentation and Android Adaptive Quality:
- Folded (Cover Screen): Quick, single-handed actions on the external display.
- Unfolded (Inner Screen): Full workspace, close in size to a small tablet.
- Half-folded: Device bent at an angle. The interface must react to the position of the hinge.
- Tabletop: The lower part acts as a stand while the upper part displays content. Key controls move to the bottom.
On foldable devices, switching between portrait and landscape occurs more frequently than on classic smartphones. The hinge angle and device position become direct signals for the interface.
What breaks when the app isn’t prepared
You open a banking app on the closed screen. You make a transfer, and halfway through entering data, you unfold the phone. At that moment in unprepared code, a clash occurs between software logic and hardware physics.
In audits, we most frequently find the same repeatable architectural errors:
- Loss of session state: The system destroys and recreates the view, causing forms to clear entered text and potentially pushing the user back to the login screen.
- Using rigid layouts: Buttons and banners stretch across the entire screen width or bunch up into a narrow strip in the middle, creating empty, useless space on the sides.
- Ignoring the physical hinge: Call to action (CTA) buttons or key texts end up directly on the fold line (hinge), making them impossible to click comfortably.
- Video and photo aspect ratio issues: Graphics in e-commerce stores get cropped, and dialog windows obstruct the whole screen with no way to close them.
- Freezing in Multi-Window mode: The app crashes the moment the user tries to resize its window to work on two apps at once.
Each of these errors stems from the same source: code written under the assumption that a device is a fixed rectangle of a single size.
The difference between a website and foldable app development
A website adapts via CSS breakpoints. Testing navigation bar behavior in split-screen is usually enough.
A native app requires architectural verification. Simply enlarging UI elements when unfolding the screen creates empty surfaces that the user doesn’t know how to utilize.
An unfolded screen opens up new possibilities: a two-panel view. A banking app displays a list of transactions on the left and details on the right without navigating back to the previous menu. Foldable app development is often a product improvement that only becomes visible after deployment.
How to check your app’s readiness for new formats
Verification doesn’t require rewriting the system from scratch. It requires walking through key user journeys across four scenarios:
- Visual comparison: Screenshots from iOS and Android simulators show rendering on the cover screen and after unfolding.
- Continuity test (App Continuity): Do form data stay in place after unfolding the screen? Does the list position reset? Does the user session disconnect?
- Hinge handling: Do key buttons overlap the fold line? Does the interface react to the opening angle of the device?
- Prioritization: Which elements require minor UI tweaks, and which require changes to business logic?
SwiftUI and Jetpack Compose reduce adaptation time. The engineering effort is noticeably lower today than it was two years ago.
Have you already audited your user journeys and interface rendering across these flexible displays? Or would you prefer to discover potential UX flaws alongside your active customers? Don’t know how your app will behave? At Tapptic, we conduct an App Audit in a few days. You get a list of issues, priorities, and an estimate.
Beyond foldable screens: how context-aware architecture transforms products
Adapting an app to foldable screens is just the first step. Official system APIs (such as Android Context Hub, Awareness API, or Apple Core Motion and DisplayPosture) allow software to read not just screen dimensions, but also the physical context of use.
The device knows whether it is standing on a table, lying flat, or in motion. The physical way of using hardware becomes a direct input signal for the interface.
What does this mean for digital products in practice?
- Financial and banking apps: On the go, on the small outer screen, the app serves a quick balance overview and NFC payments. When unfolded on a desk, it automatically switches to a full analytical dashboard with two panels and transaction history.
- B2B tools and SaaS: Bending the phone at an angle on a table (tabletop mode) automatically changes the layout — the upper part displays a presentation or video, while the lower part becomes a navigation panel with controls.
- E-commerce: On a narrow screen, the user browses a quick list of products, but after unfolding the screen gets a side-by-side comparison view of two items without switching tabs.
A new standard for software creation
Until now, mobile engineering asked: “How many pixels does this screen have?”. The new approach asks: “What situation is the user in, and what layout do they need right this second?”.
That is why building software resilient to these changes is not a one-off graphic fix for new phone models. It is a transition to a flexible architecture that automatically follows user behavior. Product teams that implement these principles today will not only eliminate UX errors on the latest flagships, but build code ready for every subsequent hardware shift.
