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Duo Support
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API reference

Every iPhone Duo API, by name

One page per symbol: what it is, what it replaces, and the mistake that brings people here. For what to change in your app, and in what order, use the compatibility checklist instead.

UIKit

AVFoundation

Info.plist

Questions

Which APIs are new for iPhone Duo?

The layout ones are UIArrangementViewController (ArrangementView in SwiftUI) for placing two views across poses, and UIViewReservedRegion for staying clear of the hinge. Bars are controlled by preferredVerticalBarBehavior. UIHingeInteraction and onHingeChange report the hinge angle, for effects rather than layout. Camera apps need AVCaptureDeviceRotationCoordinator and AVCaptureDeviceDirectionCoordinator. Most of them require the iOS 27.1 SDK.

Why is UIScreen.main deprecated?

iPhone Duo is the first iPhone with two displays, so a single global main screen no longer has a well-defined meaning — your app may be on the inner display, the outer display, or moving between them. The deprecation landed in iOS 26, before the device. Read the screen from the window scene instead, or better, use the view’s own bounds.

Do I need the iOS 27.1 SDK to use these?

For most of them, yes. UIArrangementViewController, UIViewReservedRegion, UIHingeInteraction and preferredVerticalBarBehavior all ship in the iOS 27.1 SDK. Two do not: UIScreen.main’s replacement works today, and UIApplicationSupportsMultipleScenes is an Info.plist key that has existed since iOS 13 and only became meaningful on this device.

Every symbol here is sourced from Apple’s iPhone Duo material and carries its own citations. The device ships 23 October 2026 on iOS 27.1.