UIScreen.screens.count differs on iPhone Duo sims depending on if app is IOS 26 SDK, or iOS 27 SDK

UI Frameworks UIKit
hsam OP
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Hi there,

My app uses UIScreen.screens.count (deprecated) to predict whether mirroring is happening on older iOS devices

I noticed that the number of screens is different between iOS 26 SDK apps, and iOS 27 SDK apps.

Can I expect that iOS 26 SDK apps will continue to return 1 screen like below for the iPhone Duo release?. I assume it's like this is to maximise compatibility.

App built with SDK 26 on Xcode 27.1b1 iPhone Duo sim:

UIScreen.screens.count == 1

App built with SDK 27 on Xcode 27.1b1 iPhone Duo sim:

UIScreen.screens.count == 2

Thanks for the help! Sam

Answered by Frameworks Engineer in 908343022

You should use UITraitCollection.sceneCaptureState to determine if your content is being mirrored. This works back to iOS 17.

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Frameworks Engineer OP
Apple
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You should use UITraitCollection.sceneCaptureState to determine if your content is being mirrored. This works back to iOS 17.
hsam OP

Hey, thanks for the information.

I'll take a look at this for iOS17+. I currently have minimum support set to iOS 15+, so will have to look at alternate solutions for those iOS's.

In terms of that specific UIScreen API, can I expect it to continue to return 1 screen on the Duo if my app is built with iOS 26 SDKs for the near future?

Thanks!

Frameworks Engineer OP
Apple
Accepted Answer

For pre-iOS 17 support you can check if the screen your view is on is captured – view.window.screen.captured.

I would expect that if you're seeing differences in behavior between linking against iOS 26 vs iOS 27 when running on Duo, that would continue to see those differences, but I cannot guarantee that.
hsam OP

Thanks for the information. That's helpful.