Apple has detailed how iOS 27 was rebuilt to adapt in real time to the iPhone Duo, the company's first foldable iPhone, reshaping the interface as the device folds, unfolds, and switches between its two displays.

Lock Screen controls, the Dock, and app navigation elements now sit along the side of the display instead of across the bottom, freeing up vertical space for content. When open, the iPhone Duo shows two Home Screen pages. The status bar is now a circular, flexible system that fits into the corner of the screen, and the Dynamic Island runs vertically along the side of the outer display.

The interface changes based on the device's angle, reorienting when turned on its side and switching displays when flipped. Apple required changes to how apps lay out content, including a vertical Dock. The iPhone Duo supports side-by-side multitasking with Split View, allowing two apps simultaneously or two windows of the same app. Users can swipe up to switch apps or save app pairs for later.

The software adjusts to how the phone is angled rather than just open or closed. Content shifts away from the crease when partially folded, and audio tuning accounts for speaker distance changes. When laid flat, sensors let users view content without a stand. Setting the phone down triggers StandBy on whichever display faces up. Apple built new APIs for developers, with Netflix, Zoom, and Slack already updated. The folding design enables four camera features including Smart Take, Duo Preview, Kid Cue, and Duo FaceTime.

Pre-orders for iPhone Duo open Friday, October 16, with availability beginning Friday, October 23.