Good iPhone Duo UX preserves the user’s task while changing how the interface uses space. Start with a stable information hierarchy, decide which content belongs together, and define what remains accessible when the layout becomes smaller.
Apple’s Design for iPhone Duo session recommends compact and regular size classes instead of a separate bespoke design for every pose. It also explains side-positioned controls, safe-area behavior and opportunities to show additional content on the inner display.
The examples below are proposed design exercises. They help teams translate those principles into decisions for their own products.
What should stay the same when a layout changes?
Keep the user’s place, selected item and next action understandable. A layout can rearrange content without making the customer rediscover what they were doing.
Imagine an account manager reviewing a customer record. In a smaller layout, the customer list leads to a detail page. With more space, the list and selected record can appear together. The selected customer should remain identifiable in both presentations.
Write down this continuity requirement before drawing screens. Otherwise, two polished mockups can conceal a missing transition between them.
When does a second column improve the experience?
A second column is useful when it reduces navigation or helps someone compare related information. It needs a reason to exist beyond filling the display.
| Product example | Primary task | Possible supporting content |
|---|---|---|
| Customer management | Review a customer | Recent activity or related contacts |
| Inventory | Edit an item | Stock history or warehouse availability |
| Learning | Follow a lesson | Transcript or exercise instructions |
| Booking | Select a time | Service details or booking summary |
For each example, test whether the supporting content helps the current decision. A busy activity stream can distract from an edit form. A transcript can be useful during a lesson but unnecessary on the course library page.
Define the fallback too. If only the primary content fits, decide how users reach the secondary material without losing context.
How should designers think about the fold?
Apple’s adaptive layouts session distinguishes regions that divide a display from regions that obscure it. It recommends moving related controls together where appropriate and keeping continuously scrolling content, such as articles and feeds, continuous.
The session introduces ArrangementView and UIArrangementViewController for arranging primary and secondary content. These sit between navigation and content containers; they are not a substitute for defining the product’s navigation hierarchy.
For design handoff, annotate relationships rather than prescribing coordinates for every state. For example, a playback button and progress indicator form one control group. A transcript belongs to the same task but may occupy a separate region.
Ask reviewers to follow the relationships while the interface changes. If a button appears disconnected from the content it controls, the design needs another pass.
Should hinge angle determine the whole interface?
Apple separates hinge-driven effects from layout decisions. Its multiple displays and scenes session directs developers to arrangement and region APIs for layout, while hinge observations can drive interactions or effects.
Our design recommendation is to require a task benefit before introducing a hinge effect. A playful interaction may suit a music tool; the same behavior could interrupt an administrative workflow. Define an ordinary way to complete the action so the effect does not become a hidden requirement.
What belongs in the design handoff?
Provide a compact view, an expanded view and a transition description for every priority journey. Include realistic long text, empty states, error messages and the keyboard where relevant.
Record these decisions alongside the mockups:
- Which content has priority when space is limited?
- Which controls must move as one group?
- Where does the selected item remain visible?
- How can users recover if a secondary panel disappears?
- What must QA verify beyond visual alignment?
Connect the handoff to the iPhone Duo readiness plan so design decisions become acceptance criteria.
Frequently asked questions
Do we need four independent designs?
Apple recommends an adaptive approach organized around size classes. You can still use several mockups to demonstrate expected behavior, but they should describe one coherent product experience.
Should we show more information whenever space allows?
Only when it supports the task. Extra space can also improve readability and separation between existing elements.
How do we evaluate the prototype?
Ask someone to complete the same task across changing layouts. Watch for lost selection, unexpected navigation and controls they cannot find.
For help connecting product design and implementation, start a conversation with Comms.
Further reading: Pasquale Pillitteri’s iPhone Duo developer overview provides another perspective on adapting existing apps. The technical guidance above is grounded in the linked Apple sessions.