iOS app development
iPhone apps, shipped to the App Store and kept there.
Acasa Labs builds iOS apps two ways: native SwiftUI when the app depends on Apple's platform, and Expo with React Native when the same app also needs to run on Android. Pullsy's iOS app is native SwiftUI. GymFast and NoteTube ship to the App Store from Expo codebases. We handle signing, review, and releases.
The problem
Building the app is half the work. Getting it through review and keeping it working is the rest.
An iPhone app has to pass App Store review, survive a bad network, take payments the way Apple requires, and keep working when iOS updates in September. Most delays are not in the code. They are in a rejected build, a paywall that breaks Apple's rules, or a subscription that is active on the web and missing on the phone.
What we build
- 01
Native SwiftUI apps
For apps built around the iPhone itself: widgets, notifications, background work, and the look of a first-party app. Pullsy runs on iOS 17 and up.
- 02
iOS from a cross-platform codebase
Expo and React Native when the same product needs Android too. One team and one codebase, with native modules where the iPhone needs them.
- 03
Subscriptions that agree everywhere
StoreKit through RevenueCat, entitlements synced with your backend, and the web and the app agreeing on who has paid.
- 04
App Store releases
Certificates, TestFlight, review notes, rejections, and the release that goes out on schedule. Over-the-air updates for fixes that do not need a review.
From production
From iOS apps we ship.
Native when the platform is the product
PullsyPullsy's iOS app is SwiftUI on iOS 17 and up, with push notifications when an account's numbers change. It talks to the same FastAPI backend as the web app.
Three iOS apps, one backend
GymFastGymFast ships staff, member, and trainer apps from an Expo monorepo. They share a token-authenticated mobile API, and each gym's brand colors theme the apps from one setting.
Billing that reconciles
NoteTubeNoteTube bills with Stripe on the web and RevenueCat in the apps, and a scheduled job reconciles subscriptions between them, so a student who paid on one is not locked out on the other.
Work that survives a dead zone
GymFastAn in-progress workout is saved on the device, so a dropped connection in a gym with poor signal does not lose the session.
Honest trade-offs
SwiftUI or Expo?
Choose SwiftUI if the app is iPhone-first and leans on widgets, background tasks, or heavy on-device work, or if Android can wait. Choose Expo if you need Android at the same time, or if a small team has to keep both apps moving. That is why GymFast and NoteTube are Expo apps. You can also start with Expo and add native Swift modules for the parts that need them.
What we reach for
- Swift, SwiftUI
- Expo, React Native
- RevenueCat, StoreKit
- Push notifications
- TestFlight, App Store Connect
- Sentry, PostHog
Proof
Shipped, not pitched.
01Our product
Pullsy
Instagram analytics that keep the numbers Instagram throws away.
Analytics for creators. Pullsy keeps insights Instagram discards after about 90 days, explains what each number means, grades the account, and turns it into a media kit a brand can verify.
Web · iOS (native SwiftUI) · REST API
02Our product
GymFast
Members, billing, classes, and workout plans for a gym, in one platform and three apps.
Gym management software for gym owners and personal trainers. A web dashboard and a staff app run members, plans, invoices, enquiries, and classes; members get their own branded app; GymFast Pro gives independent trainers the same tools for their clients.
Web dashboard · iOS · Android · Staff, member, and trainer apps
03Our product
NoteTube
A lecture becomes a study system: chat, flashcards, quizzes, all grounded in the source.
An AI learning platform that turns PDFs, YouTube lectures, recordings, and notes into a structured notebook with grounded chat, spaced-repetition flashcards, and graded quizzes.
Web · iOS · Android · Chrome extension · MCP server
Questions
iOS app development questions we get asked.
Do you build native iOS apps or cross-platform ones?
Both. Pullsy is native SwiftUI. GymFast and NoteTube are Expo apps that ship to the App Store and Google Play from one codebase. We recommend one or the other after we know the product.
Do you handle App Store submission and rejections?
Yes: certificates, review notes, screenshots, and the back-and-forth when a build is rejected. Rejections happen to everyone. What matters is how quickly they get fixed.
Can the iOS app share a backend with our web app?
That is how we build it. Pullsy's iOS app and web app use one FastAPI backend, and GymFast's apps share an API with its web dashboard.
How do in-app subscriptions work with our website billing?
Apple requires StoreKit for digital purchases in the app. We use RevenueCat for that and sync entitlements with your backend, so a subscription bought on the web or in the app gives access to the same features.
Who owns the App Store account?
You do. The app is published under your Apple Developer account, and we work in it as team members.
iOS app development
Have an iPhone app in mind, or one stuck in review?
Tell us what it needs to do. We will tell you SwiftUI or Expo, what it takes to ship, and what we would build first.