Build With Me · watchOS
Your Apple Watch app, in a few seconds.
On the wrist, often on the move: everything happens at a glance.
A watchOS app is built in SwiftUI with Xcode. Its main constraint is not technical: according to Apple, interactions often last less than a minute, on the wrist, sometimes on the move. Since watchOS 6 an app can work without an iPhone app; complications are built with WidgetKit since watchOS 9; and background execution time is counted in seconds. What does not fit in a glance usually belongs in the iPhone app.
Platform briefPlatform brief — an overview verified on 23 October 2026, not yet a full guided path.
Checked on
In brief
- Interface
- SwiftUI, with Xcode
- Independence
- Apps without an iPhone companion are possible since watchOS 6
- Complications
- WidgetKit since watchOS 9; ClockKit is deprecated since watchOS 10
- Background
- A few seconds at a time, and only with a complication on the active watch face
Three ways to build
Learn, build it together, or have it built.
Learn and build
This brief and Apple’s official documentation; the iOS guide covers the Swift and SwiftUI basics the watch shares.
Build it together
Reviewed case by case: a written review of the scope and architecture, while you keep the code. There is no native app published in the Bynilson portfolio yet; the answer may be a referral to a specialist.
Have it built
Bynilson does not deliver native mobile apps. What helps instead: the roadmap and brief from the project builder, to hand to a specialist studio, and the guide Hire a developer or outsource?.
Bynilson does not deliver native mobile apps: the builder gives you the roadmap and the brief to hand to a specialist studio. A request for guidance (you build, with an outside review) is reviewed case by case.
01 — On the wrist
Designed for a glance
- Under a minute
- Apple describes concise interactions, repeated many times a day. A task that needs long reading or typing has no place on the watch.
- The Digital Crown
- It scrolls and adjusts values without covering the screen with a finger.
- Always On
- Information stays visible with the wrist down: what shows then must stay readable and discreet.
- On the move
- Large targets, few choices per screen, one obvious main action.
02 — Independence
With or without an iPhone
Since watchOS 6, an Apple Watch app can be independent: it installs and runs without an iPhone companion app, and Apple recommends that model. If you also have an iPhone app, the WatchConnectivity framework passes small amounts of data or files between the two; most transfers happen in the background, while the receiving app is inactive.
03 — Complications
Complications and the limits of background work
WidgetKit
Watch face complications, as SwiftUI views, since watchOS 9.
When: To show useful information without opening the app — often the heart of a watch app.
Not when: ClockKit, deprecated since watchOS 10, for a new project.
Background tasks
The system gives the app a few seconds of background execution.
When: Refreshing a small piece of data; the app needs a complication on the active watch face to get it.
HealthKit
Health and activity data, with the person’s explicit permission; a workout session (HKWorkoutSession) tracks a workout and tunes the watch’s sensors for the activity.
When: For health and fitness features that integrate with the Health app — Apple’s Guideline 2.5.1 asks for that.
Not when: For medical claims: nothing here implies regulatory approval.
Frequently asked questions
Do I need an iPhone app to publish an Apple Watch app?
No: since watchOS 6 an app can be independent. If an iPhone app already exists, WatchConnectivity lets the two exchange data.
How do you test a watchOS app?
Xcode offers a watchOS simulator for the interface and logic. Sensors, haptics, readability on the wrist and battery are judged on a real watch.
Can I build a health app on Apple Watch?
A health or fitness app can use HealthKit, with the person’s permission and strict privacy rules. A medical function falls under other, regulatory requirements that neither this brief nor Bynilson covers.
Sources
- WidgetKitAppleChecked on 23 Oct 2026
- Using background tasks (watchOS)AppleChecked on 23 Oct 2026
- HealthKitAppleChecked on 23 Oct 2026