With two apps or two windows visible on iPhone Duo, iOS developers now need to think about width changes, continuity, side-by-side workflows, and fold-aware layouts.
The iPhone can no longer be treated as one fixed presentation
iPhone Duo can move between an outer display and a much larger inner canvas. Apps that rely heavily on fixed dimensions need to behave sensibly as the available space changes.
Two-app workflows create new product opportunities
Split View can put complementary apps side by side. A note app can sit next to research, a file manager beside a document, or a communication app beside the content being discussed.
Two windows of the same app are possible
Apple specifically highlights opening two Safari windows. For developers, multi-window thinking may become relevant to categories such as documents, file management, commerce, productivity, and reference apps.
The best adaptation may be less code than expected
Apple says developers can adapt apps using new and updated APIs in the latest SDKs, with upcoming iPhone Duo support in Xcode Device Hub. Flexible SwiftUI layouts should provide a stronger starting point than pixel-specific interfaces.
Questions people are asking after the Apple event
Does iPhone Duo support two apps side by side?
Yes. iOS 27 introduces Split View for iPhone Duo.
Can iPhone Duo open two windows of the same app?
Yes. Apple demonstrates this capability with Safari.
Will Xcode support testing apps for iPhone Duo?
Apple says iPhone Duo support is coming to Device Hub in Xcode.