# Stop using UIScreen.main — read the screen from the window scene

> iPhone Duo is the first iPhone with two displays, so a single global main screen no longer has a well-defined meaning. Apple is deprecating the API.

Source: https://iphoneduosupport.com/checklist/uiscreen-main-deprecated/

Severity: blocker
Category: layout
Applies to: swiftui, uikit, react-native, flutter, unity, capacitor
Symptom: Wrong scale factor, wrong bounds, or blurry rendering when the app is on the outer display or after moving between displays.
Sources: https://developer.apple.com/videos/play/tech-talks/111461/
Last verified: 2026-09-09

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Apple stated in *Prepare your app for iPhone Duo* that references to the main screen will be deprecated, and that apps should avoid them on two-display devices.

## Why it happens

`UIScreen.main` returns a single global screen. iPhone Duo has two: a 7.6-inch inner display at 430 ppi and a 5.4-inch outer display at 460 ppi. The two have different sizes **and different pixel densities**, and your app can move between them while running — when the user folds the device closed, the app can continue on the cover display.

A global "main screen" cannot answer "which display is this view actually on?", so any value read from it is unreliable on this device.

## The fix

Scale is a trait. Read it from the trait collection, which updates automatically when the view moves between displays:

```swift
// Before
let scale = UIScreen.main.scale

// After
let scale = traitCollection.displayScale
```

When you need the screen object itself, reach it through the window scene that actually contains your view:

```swift
// Before
let bounds = UIScreen.main.bounds

// After
let screen = view.window?.windowScene?.screen
```

For layout, prefer not to touch the screen at all. `view.bounds`, the safe area insets, and size classes describe the space your app has been given, which is what layout actually depends on — and in Split View multitasking that space is smaller than the display regardless.

In SwiftUI, `GeometryReader` and the size-class environment values cover nearly every case without a screen reference.

## How to verify

Launch the app on the inner display, then close the device so it continues on the outer display. Log `traitCollection.displayScale` and your computed sizes across the transition; the values should track the display the app is currently on.

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