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iOS. Apple. Indies. Plus Things.

Swiftjective-C: Swift, iOS, SwiftUI, and Indie Development

Swiftjective-C is Jordan Morgan's independently published blog about building excellent software for Apple platforms. It includes practical Swift, SwiftUI, UIKit, accessibility, App Intents, architecture, design, and indie development articles, plus complete code samples and long-running notes from shipping iPhone, iPad, and Mac apps.

iPhone Duo: First Developer Good-to-Knows

// Written by // // Read it in about 3 minutes // RE: Swift

This post is brought to you by Clerk. Add secure, native iOS authentication in minutes with Clerk’s pre-built SwiftUI components.

It’s time for Apple to get into the… fold… with foldables. Anyways, on the day of the announcement, Cupertino and Friends™️ dropped six new videos over developing, designing, and crafting great apps for the nascent device:

  1. Design for iPhone Duo
  2. Prepare your app for iPhone Duo
  3. Raise the bar with iPhone Duo
  4. Strike a pose with adaptive layouts on iPhone Duo
  5. Leverage multiple displays and scenes on iPhone Duo
  6. Build a great camera experience for iPhone Duo

And there’s some ground to cover, because it seems like this thing can contort your app’s layout about 7,000 different ways:

Mail adapting to six iPhone Duo layouts, including closed, open, landscape, portrait, and partially folded poses.

I’ve only watched one, and the other five are next for me to marathon, but in the interim I had Astra check out each one because I’m excited and impatient. Here’s what it thinks the critical things to know are, with the obvious caveat that this is at the discretion of an agent.

let concatenatedThoughts = """

These takeaways come from Apple's English video captions. Some new iOS 27.1 API reference pages weren't available at writing; documentation links below point to available references, with timestamps for the new APIs.

"""

astra / session notes
AI-generated summary

The following section was generated by Astra from Apple's video captions. Follow the linked videos and documentation for the original guidance.

Build With iOS 27.1

Existing apps run, but rebuilding with the iOS 27.1 SDK enables edge-to-edge content and vertical bars. Use Xcode 27.1’s Device Hub to test opening, closing, rotating, and partially folding; its updated App Resizability skill also covers SwiftUI and Duo.

Size Classes Beat Device Assumptions

Duo remains an iPhone even when its inner display has regular width and height size classes. Use size classes and local view or scene geometry; avoid layout branches based on idiom, interface orientation, or UIScreen.main. The inner display doesn’t honor supported interface orientations for normally resizable apps.

Keep the Same App Inside and Out

Use the extra space for columns or richer navigation while preserving the same hierarchy and functionality across poses. NavigationSplitView and UISplitViewController adapt automatically. A tabletop layout can put media above controls, but opening or folding the phone shouldn’t be required to access a feature.

Safe Areas Are Asymmetric

Vertical controls can occupy either edge, especially in Split View. Handle each safe-area inset and layout margin independently: keep interactive content inside, let backgrounds extend behind bars, and test your app on both sides of the inner display.

Let Containers Move Your Bars

Use bars managed by navigation and tab containers; standalone UIKit bar instances don’t participate in the new vertical layout. Supply both titles and symbols so the system can choose a representation. Custom controls need an explicit vertical opt-in and must fit the bar’s fixed width; meaningful text can stay horizontal.

Decide What Overflows First

Toolbars compress before tabs by default; task-focused screens can change that preference. Give frequent actions and status-bearing items higher visibility priority, and consolidate custom overflow actions into ToolbarOverflowMenu or UIKit’s additionalOverflowItems so users get one system overflow menu.

Move Controls Away From the Fold

System sheets, alerts, and menus already avoid the fold. For custom layouts, query reservedRegion on GeometryProxy or UIView: division regions describe the fold, while occlusion regions describe obstructions such as the active inner camera. Reposition important controls; continuous scrolling articles, feeds, and lists don’t need displacement.

Arrangements Handle Two-View Layouts

ArrangementView and UIArrangementViewController adapt two views around available space and the fold. Choose split when both views must remain unobscured, or overlay for a foreground/background relationship. Arrangements provide layout, not navigation: avoid placing navigation containers inside them or embedding arrangements inside lists and scroll views.

Hinge Angles Drive Effects

onHingeChange and UIHingeInteraction expose discrete hinge states and continuous angles for interactions like a musical pitch bend. Handle a missing hinge on other devices and reset effects when appropriate. Use arrangements and reserved regions for layout decisions.

Multitasking Can Change Both Dimensions

Side-by-side apps reduce width; pinned Picture in Picture can reduce height. Duo also supports multiple instances of your app, but new windows can only be created on the inner display. Handle scene-request errors; UIWindowScene.ActivationAction automatically hides when opening another window is unavailable.

Camera Apps Can Use Both Displays

CameraCaptureAccessory can show a subject-facing preview or teleprompter on the outer display while the main camera UI occupies the inner display. It requires a full-screen app on the inner display and an active camera session. Register it with the camera view and observe availability changes.

Choose Automatic Camera Switching or Full Capabilities

Front-camera discovery using wide or ultrawide types returns a virtual front camera that switches between displays automatically, limited to 1080p/60fps and no depth. Access the physical cameras individually for depth or the outer camera’s higher limits—up to 4K and 120fps—but manage switching yourself.

Camera Position Isn’t Camera Direction

A camera marked .front can face away from the person using your app. AVKit’s AVCaptureDeviceDirectionCoordinator reports direction relative to a view; use one per display view. Its callback runs on the main actor: pass the sendable AVCaptureDeviceDescriptor to your camera actor before reconfiguring capture, then update preview mirroring and UI.

Revisit Preview Framing and Rotation

Use preview videoGravity to choose fit versus fill, and dynamic aspect ratios to exploit the square front sensors. Adopt AVCaptureDevice.RotationCoordinator for upright previews and captures across display changes; after adopting it, disable camera-sensor-orientation compensation to improve performance.

> _ end of agent notes

Until next time ✌️

···

The Spend Stack Revival

// Written by // // Read it in about 1 minutes // RE: The Indie Dev Diaries

This post is brought to you by Clerk. Add secure, native iOS authentication in minutes with Clerk’s pre-built SwiftUI components.

Ah, Spend Stack. I’m pleased to announce that everyone’s favorite finance app/running total list thingy/do-it-all-calculator-with-1000-use-cases-but-not-one-clearly-defined is coming back from the dead…again! The previous owners, who had let me open source it, have given me back full IP rights. She’s back home:

Spend Stack restored to Jordan's App Store Connect account.

If you need a refresher, Spend Stack was my first indie darling. It was well received among press and had a few fans over at Apple, but I never could quite figure out what exactly it was (spoiler, I still haven’t) or how to monetize it. It was originally sold around the covid-era, with a blog post from me covering the details here:

And, so it is, nearly six years later, I guess Spend Stack has a new home, again. Which is back home! For now, I’m not going to change much about it, here’s my plan:

  1. This thing is old. Most of it is in Objective-C. I have Codex on a loop modernizing it now. I’ll get it buiding in a Swift-first rewrite.
  2. Then, I’ll integrate modern APIs such as GRDB and CKSyncEngine.
  3. I’ll make the app free (it launched as a paid up front app), with an optional $9.99/yr sub for cloud sync.
  4. And once it’s stable, I’ll open it up for TestFlight.

It warms my heart that, years and years later, I’ll still get a random, out-of-the-blue Spend Stack message from someone. I don’t know where it goes from here, but I can bring it back as it once was without too much hassle in the age of agents. And, if we’ve become internet friends post-Spend Stack era, here’s most of what I wrote about it if you’d like to catch up:

Here’s to new, old beginnings!

Until next time ✌️

···

Introducing Indie Walks

// Written by // // Read it in about 1 minute // RE: The Indie Dev Diaries

This post is brought to you by Clerk. Add secure, native iOS authentication in minutes with Clerk’s pre-built SwiftUI components.

For a long time, the homies and I have joked about starting a podcast.

Spoiler: we will never actually start a podcast. But, it would be fun though.

The idea of a podcast is tantilizing. I love talking shop, writing about indie life, or chatting with anyone about the ongoings of our insane vocation. And while I’ve written on this blog for years now, I do love talkin’.

So, introducing…

Indie Walks

Short form video essays/journals/episode/talk show??? from me over indie stuff. So, MRR, web to app, how to manage time as a parent with side projects, that kind of stuff. You can watch the first episode wherever is best for you:

  1. X
  2. Threads
  3. Instagram
  4. Episode Directory

And, as linked above, I’ll keep that evergreen page up to date here with each new episode. I hope you’ll follow along, and feel free to shoot over any questions or suggestions for topics.

Until next time ✌️

···

The Skills Conundrum

// Written by // // Read it in about 12 minutes // RE: AI

This post is brought to you by Clerk. Add secure, native iOS authentication in minutes with Clerk’s pre-built SwiftUI components.

Skills are a paramount puzzle piece to my agent usage. The rub? They are too easily fragmented:

  1. You could be using different agents. Claude, unlike other agents, looks at its own spot for skills. Everything else uses an open standard, ~/.agents/skills.
  2. Then, there’s different machines you could be running. Symlinking is great, but run npx skills update on your MacBook at home and then your MacBook on the go is now stale.
  3. Each harness seems to want to funnel you into different paths for installing skills.

Is there an open standard to solve? Surely, if there is, it would have to be cloud based. For example, at Superwall, we simply have GitHub repo for proprietary, shared skills. So, I’ve adopted that same pattern for two things:

  1. The skills I’ve personally made, and just as important…
  2. Skills I’ve installed via Vercel’s skills.sh.

The whole process hinges on three skills: push-my-skills, pull-my-skills, and sync-npx-skills. So, uhhh, naturally - I made a Windows XP recreation to show you how the process works. You got two computers, each needing to be current on 3rd party skills from skills.sh, and my own personal ones. Click on any of the skill buttons below to see how they operate:

Skills Sync Center

My Network Places Choose a job below to watch it travel.
At home

MacBook A

My source filespersonal-skills/
Agent copiesClaude · Codex · more
npx lockWhat is installed here
The handoff

GitHub

Skills I madeDreamingInBinary/skills
Third-party manifestDesired state + baselines
On the go

MacBook B

My source filespersonal-skills/
Agent copiesClaude · Codex · more
npx lockWhat is installed here
THE WHOLE IDEA

Two kinds of skills. One cloud handoff.

Your skills no longer depend on whichever Mac or agent you happened to use last.

  1. 1

    Skills you authorPush the real files up; pull them down elsewhere.

  2. 2

    Skills you installPublish the list; reconcile each Mac against it.

  3. ✓

    Installed folders are copiesGitHub is the durable source of truth.

Ready. Pick a job to run.

Here’s the technical breakdown.

For the skills that I’ve made… …one GitHub repo is the source of truth; so everything inside ~/.agents/skills is merely an installed copy. On one Mac, push-my-skills refreshes those copies, commits my changes and pushes them to GitHub in one shot. On another, pull-my-skills pulls that repo and reinstalls the same skills for every agent. Now, my personal skills are source controlled and current across machines.

But, that’s just half of it. Third-party skills actually use a shared manifest instead…

…so sync-npx-skills compares that manifest against the Mac’s last sync and its current npx lock file, determining whether a difference was made here, or on another machine. Local additions and removals are published; which means remote changes are applied so each Mac eventually converges on the same set of skills without manually copying folders around.

At this point, I have to ask: Did I solve the problem? Absolutely. Did I engineer myself into a small pyrrhic victory along the way? Also absolutely maybe yes! My hope is that an open standard arrives tomorrow, and makes all of this gloriously obsolete. Until then, at least both Macs agree on what skills they have.

Until next time ✌️

···

Copywriting with Agents and...Apple Designers?

// Written by // // Read it in about 5 minutes // RE: AI

This post is brought to you by Clerk. Add secure, native iOS authentication in minutes with Clerk’s pre-built SwiftUI components.

It’s hard not to have tragic copywriting as a programmer. As we stepped into this indie scene, it was (and is) all too common to ship something like this:

The Button Label Test

What will happen when you tap it?

New Event
Design review Today, 2:00–2:30 PM

The action stays the same. Only the words get clearer.

Even nearly 15 years (!!!) into this business, I can still fall into this trap. Left to my own devices, I’ll happily ship some gormless button label like “Initiate Sequence”, its copy that reads like it was written for someone who should be code reviewing a recursive function. But instead, most people who use my apps are the everyman, who isn’t serially online chatting about AI agents. Writing for them doesn’t come as naturally. Other than experience and being aware of it, is there a way to audit your interface controls for terrible copywriting?

Turns out, Apple has the answer. And, if you power it up with an agent, it can audit your entire app for you. It all starts with this banger session:

Apple Developer app showing the WWDC26 session Craft clear names for features and labels in your app.

In it, Heej walks through how to craft copy that feels human. That really helps someone understand the impact of a button press, or simply set an expectation of what will happen. This kind of thing is absolutely gold. It is the number one thing I think people like me struggle with. Here’s how I hooked up an agent to learn about that session, and then apply it to one of my apps:

  1. Install Sosumi MCP or install the WWDC.ai skill.

    For Sosumi MCP:

    claude mcp add --transport http sosumi https://sosumi.ai/mcp

    Or, for the WWDC.ai skill:

    npx skills add https://github.com/superwall/skills --skill wwdc --global --yes --agent claude-code universal
  2. Have an agent watch that session via whatever you installed on step 1.
  3. Then, point it your app and give it context on who your target market is, what your app does, and using its new copywriting knowledge - propose updates to strings throughout.

When I did this, I had fantastic results:

A code diff showing clearer share-link copy proposed across an app.

Some of them were so obvious, it hurt. But, this is just a blindspot I have. I’m not great at interface label naming, or naming in general. There’s a lot of talk about where the line should be with creativity and AI, and it’s a necessary discourse. In this case? This is one area where I’m happy to have its help.

Until next time ✌️

···
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