How to build a fitness app for iOS
What a fitness app needs
- A library of workouts or programs with exercises
- A logging flow for sets, reps, time, or distance
- Progress charts and personal records
- HealthKit to read and write activity data (optional)
- Reminders and a Home Screen widget
- Accounts and sync if programs are shared (Supabase)
The MVP slice is a set of workouts, a logging flow, and progress charts. Coaching, social feeds, and custom program builders come after.
Core screens and data
A fitness app needs a workout library, an active workout screen, a set logger, a progress view, and profile or settings screens. Here is how those screens map to the data each one stores.
| Screen | What it does | What it stores |
|---|---|---|
| Workout library | Browses workouts and programs by type or muscle group | Workout definitions, exercises, and target sets and reps |
| Active workout | Guides you through a session one exercise at a time, with a rest timer | The in-progress session and the timer state |
| Set logger | Records sets, reps, weight, time, or distance | Logged sets with weight, reps, and a timestamp |
| Progress and records | Charts volume over time and lists personal records | Historical sessions and per-exercise personal bests |
| Health sync | Reads and writes activity to HealthKit | Workout summaries, heart rate, and calories, with permission |
| Reminders and widget | Sends workout reminders and shows today's plan | Scheduled reminder times and today's workout snapshot |
| Profile and settings | Handles account, units, and the paywall | Units preference, account (Supabase), subscription status |
How to build it with AppFlight
Describe it, for example: "A fitness app with guided workouts, a logger for sets and reps, progress charts, HealthKit integration, and a daily reminder." AppFlight plans the screens, generates native SwiftUI, runs it in a live simulator, and can include a Home Screen widget. Connect Supabase if you want shared programs and accounts. You iterate by asking for changes in plain language.
Starter prompt
This is the exact plain-English prompt you can paste into AppFlight to start a fitness app. It covers the workout library, the logging flow, HealthKit, a widget, Supabase accounts, and a RevenueCat paywall, so the first build reaches the core loop.
Build a fitness app for iPhone. Give me a library of guided workouts grouped by muscle group, and a program view that schedules workouts across a week. When I start a workout, walk me through each exercise and let me log sets, reps, and weight, with a rest timer between sets. Add a progress screen with charts of my volume over time and a list of personal records, and write completed workouts to HealthKit. Include a daily reminder and a Home Screen widget that shows today's planned workout. Use Supabase for accounts so shared programs sync across devices. Add a RevenueCat paywall where a subscription unlocks the full program library and advanced stats.
Monetization for a fitness app
Workout content and programs are digital, so a subscription that unlocks them uses in-app purchase. RevenueCat manages it and Superwall lets you test paywalls without shipping an update. A price around five to ten dollars a month is common for this category. If you sell in-person classes or one-to-one personal training, that is a real-world service and can run through Stripe. Match the payment method to what is being sold.
Shipping it to the App Store
When it works in the simulator, AppFlight signs the build, uploads to TestFlight so you can test the workouts and HealthKit prompts on your device, then submits to the App Store with metadata and screenshots. If Apple rejects the build, AppFlight reads the reason, fixes it, and resubmits. Apple reviews every app, so a submission is not the same as an approval, but the pipeline runs without you opening Xcode.
FAQ
Does a fitness subscription use in-app purchase?
Yes. Workouts and programs are digital content, so unlocking them with a subscription requires in-app purchase, which RevenueCat manages.
Can it use HealthKit?
Yes. HealthKit can read and write workouts, steps, and heart rate. AppFlight builds the integration in native Swift; Apple requires a clear reason for the data.
Can it show a widget?
Yes. WidgetKit gives you a Home Screen and Lock Screen widget for today workout or streak, which AppFlight can build.