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

iPhone Duo does not ship on iOS 27. It ships on iOS 27.1, on 23 October 2026, and the difference matters if you are building for it. This post covers both: what shipped in iOS 27 on 14 September, and where 27.1 stands.

iOS 27.1: the release iPhone Duo runs

iOS 27.1 is the version that carries the iPhone Duo behaviours — the SDK tier at which your app reaches the screen edge and bar buttons lay out vertically. The iOS 27.1 SDK is in Xcode 27.1 beta, released on 18 September.

The unusual part, checked against Apple’s releases feed on 5 October 2026:

• There has been no public iOS 27.1 beta at all. Not one.
• iOS 27.2 has had two betas already, on 16 and 21 September — a release after 27.1.
• iOS 27.0.1 shipped on 28 September as a maintenance update to 27.
• Xcode 27.1 is still on its first beta, while Xcode 27.2 reached beta 2 on 28 September.

So the OS that ships on every iPhone Duo sold on 23 October has not been in anyone’s hands outside Apple. For developers that means the simulator in Xcode 27.1 beta is the only place to see your app on this platform before customers do. We track that on the Xcode 27.1 status page.

If you want the practical version — what breaks and in what order to fix it — start with what to fix first.

What shipped in iOS 27

iOS 27 became available on 14 September 2026. It is a large release, but most of it falls into a few themes: a rebuilt Siri, more Apple Intelligence inside everyday apps, a noticeably faster system, and stronger tools for families. Here is what is new, and where the limits are.

At a glance

• Siri AI, a more capable and conversational Siri, rolls out in beta in English.
• Apple Intelligence comes to more apps, including Photos, Safari, Phone, Messages and Mail.
• Performance: Apple says apps launch up to 30% faster, new photos load up to 70% faster and AirDrop is up to 80% faster.
• Liquid Glass gains a slider that ranges from ultraclear to fully tinted.
• Parental controls are redesigned, with website approvals and time allowances.
• iPhone Handoff lets you move between two iPhones that share one phone number, on supported carriers.

Which iPhones get it

iOS 27 supports iPhone 11 and later, iPhone SE (2nd generation and later) and the new iPhone Duo. The Apple Intelligence features need a more recent model: iPhone 15 Pro, iPhone 15 Pro Max, or any iPhone 16 or later.

Siri AI

The headline change is Siri AI, a new version of Siri powered by Apple Intelligence. You can type or talk to it naturally, ask follow-up questions, and have it use personal context, such as information in your own apps, alongside broad knowledge from the web. It can see what is on screen and act on it, and it can take actions in apps including Messages, Music and Reminders.

Siri also gets a dedicated app that keeps conversations in one place across your devices, and a choice of voice with adjustable expressiveness and pace. Write with Siri works almost anywhere you type, drafting text or giving feedback on what you have written.

Availability is narrower than the rest of the release:

• It launches as a beta in English. French, Japanese, Korean, Portuguese and Spanish follow in October.
• It is not available on iPhone in the EU at launch, or in China while it is under regulatory review.
• It is not available to users under 13.

Apple Intelligence across apps

• Photos: new editing tools, including Spatial Reframing, Extend, and an upgraded Clean Up.
• Image Playground: higher-quality images in a wide range of styles, including photorealistic.
• Camera: a Siri mode that uses Visual Intelligence to search, ask questions and take action on what is in front of you.
• Safari: tabs grouped automatically by topic, and Notify Me alerts when a page changes, such as a restock or a price drop.
• Phone: Call Context surfaces relevant details during business calls, such as a confirmation or reservation number.
• Messages and Mail: suggested quick actions based on the conversation.
• Shortcuts: describe an automation in plain language and have it built for you.

Apple notes that some of these features have daily usage limits, with expanded access available for a fee.

Faster everyday use

iOS 27 puts real effort into responsiveness. Apple’s own figures:

Wi-Fi and cellular hand-offs are smoother, Mail search ranks results by relevance, and there is a long list of smaller refinements across the system.

Design

Liquid Glass, introduced last year, gets refinements for readability and a new slider in Settings that adjusts its look from ultraclear to fully tinted. App icons have also been redrawn to look sharper.

For families

Parental controls are redesigned around expert guidance:

• Ask to Browse requires a child to request permission before opening a new website, with approval sent through Messages.
• Communication Safety now also detects gore and violence, as well as nudity, in shared images and video.
• Time Allowances and Schedules set limits by category, such as games or social media, with age-based guidance.

Also new

• Automatic captions for videos, with translation of existing captions
• iCloud Shared Albums with full-resolution sharing, and easier access for friends on Android or Windows
• Perimenopause and menopause support in Cycle Tracking
• Custom EQ for AirPods
• Flyover in Maps combined with Visual Intelligence
• GymKit on iPhone, connecting to compatible cardio equipment

What it means for app teams

iOS 27 is also the foundation for the first foldable iPhone. Three points for anyone shipping an app:

• iPhone Duo goes on sale on 23 October running iOS 27.1. Apps built with the iOS 27.1 SDK reach the edge of its screen, and inherit its side-mounted toolbars. The compatibility checklist covers what to fix first.
• Check custom colours against the Liquid Glass slider. People can now set system chrome anywhere from ultraclear to fully tinted, so it is worth checking text and brand colours at both extremes. This is our advice rather than Apple’s guidance.
• Design for both displays. Apple’s new guidelines set out how controls, reserved regions and the fold should be handled; our summary of the iPhone Duo design guidelines walks through them.

Feature availability varies by language, region and device. Apple’s iOS 27 page has the full details and footnotes.