Blog

Framework-by-framework guides to iPhone Duo. Posts marked analysis cover frameworks whose vendors have shipped no iPhone Duo support — those conclusions are ours, and the posts say so.

React NativeAnalysisLatest

React Native libraries on iPhone Duo: what shipped, and what is still a pull request

react-native-screens shipped iPhone Duo support today. React Native's own fold API has been an open pull request since 18 September. Checked library by library.

13 Oct 20266 min read

The webAnalysis
iPhone Duo and CSS breakpoints: your framework thinks it is a phone
Tailwind's first breakpoint is 640px. iPhone Duo's inner display is 626. In three of five major CSS frameworks, a 7.6-inch screen gets the phone layout.
7 Oct 20268 min read
All frameworksAnalysis
iPhone Duo points vs pixels: which figures are right
iPhone Duo is 1878 × 2670 pixels inside and 1398 × 2034 outside. Divide by three for points. Why sources disagree on the points, and how to check any of them.
23 Sept 20263 min read
All frameworksApple-documented
Xcode 27.1 beta is out: test your app on iPhone Duo
Apple released Xcode 27.1 beta on 18 September with the iPhone Duo simulator. What it needs, what it cannot test yet, and what to check first.
19 Sept 20265 min read
React NativeAnalysis
Expo on iPhone Duo: EAS Build, app.json and native tabs
An Expo app is a React Native app, but three Expo-only choices decide what iPhone Duo shows: the EAS build image, app.json, and which tab bar Expo Router draws.
15 Sept 20266 min read
All frameworksAnalysis
Why vibe-coded apps break on iPhone Duo
Apps built with Rork, Bolt or Replit Agent are Expo apps underneath. The generated patterns that break on Apple's foldable, and a prompt to fix them.
15 Sept 20268 min read
All frameworksApple-documented
iOS 27 and 27.1: which one iPhone Duo actually ships with
iPhone Duo ships on iOS 27.1, not iOS 27. What is in each release, why 27.1 has had no public beta, and what that means if you are building for the device.
14 Sept 20265 min read
All frameworksApple-documented
iPhone Duo Human Interface Guidelines, explained
Apple says do not design a layout per pose — design for two size classes. The iPhone Duo Human Interface Guidelines in plain terms, and what each rule means.
14 Sept 20266 min read
All frameworksAnalysis
The foldable era: your app now has to survive nine screen shapes
Phones were all roughly 2.17:1. Shipping foldables run from 1.04 to 2.37 — and change shape while your app is running. What that means for layout.
13 Sept 202612 min read
All frameworksAnalysis
iPhone Duo vs Samsung Galaxy Z Fold: what differs for developers
Both are 7.6 inches, neither is the same shape: 1.42 inner aspect on iPhone Duo against 1.33 on the Z Fold 8. The displays, the fold APIs, and what porting costs.
12 Sept 20265 min read
The webAnalysis
Websites on iPhone Duo: Safari can't see the fold
Chrome has shipped the Viewport Segments API for foldables. Safari has not, and WebKit has taken no position on it. What that means for your site on the new iPhone.
12 Sept 20266 min read
All frameworksApple-documented
Prepare your app for iPhone Duo: what to fix first
Four assumptions break on iPhone Duo: fixed widths, orientation locks, symmetric safe areas and idiom checks. Fix those first — the rest can wait past 23 October.
10 Sept 20267 min read
Capacitor & webAnalysis
Capacitor, Cordova and web views on iPhone Duo
Hybrid iOS apps adapt best to the foldable iPhone, because CSS was built for variable viewports. An analysis of the few things that still break.
9 Sept 20266 min read
FlutterAnalysis
Flutter on iPhone Duo: the right abstraction, possibly unwired
Flutter already has a foldable API from Android — MediaQuery.displayFeatures. An analysis of whether it reaches iPhone Duo, and what to do either way.
9 Sept 20267 min read
React NativeAnalysis
React Native on iPhone Duo: what breaks and what works
Meta has shipped no iPhone Duo support. Which React Native patterns break on the foldable display, which survive, and where a native module becomes unavoidable.
9 Sept 202610 min read
SwiftUIApple-documented
SwiftUI on iPhone Duo: adaptive layout and transitions
A walkthrough of the SwiftUI APIs for iPhone Duo — ArrangementView, ReservedRegion, size classes and vertical toolbars — in the order that actually works.
9 Sept 202610 min read
UIKitApple-documented
UIKit on iPhone Duo: vertical bars and arrangements
A UIKit toolbar item with no icon never moves to the side column. That, and the rest of what changes on iPhone Duo: arrangements, reserved regions, UIScreen.main.
9 Sept 20269 min read
UnityAnalysis
Unity games on iPhone Duo: resolution changes mid-play
Games have a harder iPhone Duo problem than apps, because resolution is usually treated as a launch-time constant. An analysis of what changes in a Unity iOS build.
9 Sept 20266 min read

Blog

React Native libraries on iPhone Duo: what shipped, and what is still a pull request

iPhone Duo and CSS breakpoints: your framework thinks it is a phone

iPhone Duo points vs pixels: which figures are right

Xcode 27.1 beta is out: test your app on iPhone Duo

Expo on iPhone Duo: EAS Build, app.json and native tabs

Why vibe-coded apps break on iPhone Duo

iOS 27 and 27.1: which one iPhone Duo actually ships with

iPhone Duo Human Interface Guidelines, explained

The foldable era: your app now has to survive nine screen shapes

iPhone Duo vs Samsung Galaxy Z Fold: what differs for developers

Websites on iPhone Duo: Safari can't see the fold

Prepare your app for iPhone Duo: what to fix first

Capacitor, Cordova and web views on iPhone Duo

Flutter on iPhone Duo: the right abstraction, possibly unwired

React Native on iPhone Duo: what breaks and what works

SwiftUI on iPhone Duo: adaptive layout and transitions

UIKit on iPhone Duo: vertical bars and arrangements

Unity games on iPhone Duo: resolution changes mid-play