# React Native on iPhone Duo

> React Native has shipped no iPhone Duo support. Core layout works, but the new adaptive APIs need a native module and several common patterns break.

Source: https://iphoneduosupport.com/frameworks/react-native/

Support status: none
No first-party support. Flexbox layout adapts, but cached dimensions, orientation locking and safe-area assumptions all need attention.
Last verified: 2026-09-09

---

Meta has not shipped iPhone Duo support and has published no guidance for it. What follows is our analysis of how React Native behaves against Apple's documented behaviours.

## The good news

Flexbox is inherently adaptive. A React Native layout built with flex ratios rather than fixed pixel values reflows correctly on the inner display without changes, because the native view hierarchy is resized by UIKit underneath.

## What breaks

**Cached dimensions.** `Dimensions.get('window')` read once at module scope is the single most common failure. It captures a size that changes when the device folds, rotates, or enters Split View. Use the hook, which re-renders on change:

```jsx
const { width, height } = useWindowDimensions();
```

**Orientation locking.** Locking to portrait in `Info.plist` or through a library does not work on the inner display, which ignores supported interface orientations. Your app will be laid out in configurations you did not design.

**Safe area assumptions.** `react-native-safe-area-context` reports real insets, but application code frequently collapses them — taking the larger of left and right, or applying one horizontal padding value to both sides. Those insets are now genuinely different. Apply `insets.left` and `insets.right` separately.

**Fixed dimension styles.** `width: 390` and `Dimensions.get('window').width * 0.5` computed at render-time-once have the same problem as native fixed frames.

## What is unreachable today

`ReservedRegion`, `ArrangementView`, hinge angle, scene accessories, and the vertical bar APIs have no JavaScript bindings. Reaching them requires a native module wrapping the Swift API and bridging values into JS. Until someone ships that, a React Native app can be *correct* on iPhone Duo but cannot be *hinge-aware* — it cannot avoid placing content across the fold.

For most apps correctness is enough. For a canvas, editor, or game where the fold matters, budget for native work.

Full analysis: [React Native on iPhone Duo](/blog/react-native-iphone-duo/).

---

Published by iPhone Duo Support (https://iphoneduosupport.com). Not affiliated with Apple Inc.