Issue 769

25^th September 2026

Written by Alex Ozun

Comment

Last week I attended the iPhone Duo Group Lab, and while none of my questions made it to the panel, I came out with a few insights. I was as interested in the questions other developers asked as in Apple’s answers. It’s clear to me that the new hardware sparked a lot of imagination. Developers are eager to explore creative app ideas that the new device enables.

For example, are third-party StandBy apps that use the Tent pose, like Apple’s glowing alarm clock, supported? Or can apps receive touch input from both the inner and outer displays simultaneously when in the Laptop pose (for hot-seat gaming perhaps)? The answer to both questions seems to be ‘No’, at least for now as the panelists acknowledged that they themselves don’t yet know all the ways people will physically use Duo.

Then there’s the hinge. Can the hinge angle be creatively used as input? For this, the panelists suggested a hilariously brilliant idea of a virtual band app, where the hinge can be used as an electric guitar whammy bar, or an accordion bellows, or as a piano when in the Laptop pose. Honestly, somebody should just build this!

Speaking of the hinge angle change, in the middle of the Lab, one of the panelists mentioned that the new Device Hub comes with a realistic model of Duo that can be freely rotated in 3D space, along with a hingle-angle slider. Wait, what?! Did we miss it in the latest Xcode 27.1 beta? Turns out it’s just hidden behind a feature flag, and folks already figured out how to enable it. Take it for a spin (literally), it’s really cool! I initially had mixed feelings about Device Hub, but seeing that Apple approaches it not merely as another simulator wrapper with menus, but as an immersive device simulation environment, it starts to make a lot more sense.

Wrapping up thoughts on the iPhone Duo Group Lab, for all the creativity and imagination reflected in the community questions, the overarching message from Apple was to treat Duo as an iPhone that folds and resizes, not as a separate platform. The new hardware creates opportunities, but developers shouldn’t try to invent a gimmick for every pose and hinge angle.

But there’s no harm in having a bit of fun, right? 😉

– Alex Ozun

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Tools

I love SF Symbols! And I love unapologetically native macOS apps (aka Mac-assed apps). Amy Worrall combines both of these beautifully in McKinley.

Creating custom SF Symbols and syncing them with Xcode’s asset catalogue is still more fiddly than it should be, which makes McKinley a compelling all-in-one tool, check it out!

The Nil Coalescing team has been a trusted source of SwiftUI and Swift knowledge in Apple Community for years now, so it only makes sense for them to distill and package that knowledge into a tool for AI agents. I like that it’s not just another skill, but an MCP-enabled tool that can plug into an agentic harness for better experience and improved token efficiency.

Code

Serg Dort addresses an increasingly common problem for Apple developers: switching between agentic and hands-on workflows while sharing the same Xcode build environment.

The article shows how to configure Xcode’s compilation cache so that a handoff from a headless AI agent to a human in Xcode still benefits from incremental build times.

Harking back to the iPhone Duo Tech Talks and Labs, Apple clearly positions ArrangementView as one of the heavy lifters for iPhone Duo adoption, so it’s worth taking the time to understand it properly.

What I found particularly valuable in this article by Fatbobman is that it focuses on the semantics behind ArrangementView, helping us build intuition rather than merely learn a new API. The key insight is that ArrangementView declares the relationship between two views rather than geometry. As the title suggests, it pushes us to think before we arrange. I love this message!

It’s that time of year when we get tons of new APIs that aren’t available on previous OS versions. Backporting is a common way of dealing with this challenge. There are many ways to approach backporting, but I like the type-safe, idiomatic, and lintable Backport API that Majid proposes in this article. I also like how it demonstrates the new anyAppleOS availability qualifier!

Figuring out how to deterministically test Unstructured Concurrent Swift code is no mean task (trust me, I tried)!.

Michal aptly points out how both humans and even the latest models often resort to sprinkling sleep calls into tests, hoping to shoehorn racing tasks into some semblance of an ordered queue. We all know how this usually ends. Michal outlines a better solution based on the Test Spy technique, where objects performing racing tasks can be swapped for controllable test doubles that can produce values or advance time deterministically in tests. Neat!

And finally...

macOS 27 comes with the Liquid Glass transparency slider. But what if we could keep pulling the slider out of the settings window? 🤔