E-commerce and marketplace
Birmarket, a marketplace with 2M+ customers: delivery, cart, promotions, Premium Subscription, and the loyalty program. Earlier, the online store of a US sports-nutrition business.
Max Vilchevskiy
Kyiv, Ukraine
Senior iOS Engineer
Swift · SwiftUI · UIKit
I take iOS features from idea to App Store release. At Birmarket I helped split a large marketplace app into modules and built an SDK shared across three apps.
- 10+ years in iOS, including freelance and contract work
- Built the Premium Subscription SDK that shipped in Birmarket (2M+ customers), the Birbank banking app and the M10 wallet
- Rebuilt Birmarket's subscription onboarding and A/B-tested it from five screens to three, which raised new-subscriber conversion
- Owned the Apple Watch client of a voice AI assistant for field workers end to end
- Built the Drinkit iOS app from scratch with two other iOS engineers. It took about 95% of orders as the chain grew to eight shops
What I have worked on
Products I built iOS features for.
Complex UI
Drinkit's dynamic menu, built for each customer from the backend catalog by preference and time of day, with looping drink videos and drink customization. At Birmarket, moved 15+ screens from UIKit to SwiftUI.
Payments and fintech
A subscription SDK shipped in the Birbank banking app and the M10 wallet, a payment SDK integration at Drinkit, and KYC, Stripe and Apple Pay in a gold-trading app.
Maps and geofencing
Parking search on Google Maps with Core Location at Tap4Parking, location-aware offers near Drinkit shops, delivery addresses at Birmarket, and arrival detection with a monitored region for the Apple Watch assistant.
Watch and devices
An Apple Watch voice assistant at GlobalLogic and Bluetooth tracker prototypes on CoreBluetooth at GBKSoft.
How I build
The engineering side, with where I did it.
Modular architecture
Helped split the Birmarket monolith into more than thirty modules and carried about seven of them myself, among them profile, partners and deep-link handling.
One SDK in three apps
Rebuilt Premium Subscription as an SDK with SwiftUI and Clean Architecture for Birmarket, the Birbank banking app and the M10 wallet. Host apps own authentication and pass in a scoped token. The SDK owns its networking.
Testing
Unit and integration tests for prices, cart state and totals. Raised the subscription module's unit-test coverage from about 15% to 80% and refactored the module.
Performance
Moved network calls off the main thread at Birmarket, which removed scroll freezes, and fixed a retain-cycle crash at Drinkit with the Memory Graph Debugger and the Leaks instrument.
Swift Concurrency
Swift Concurrency at Birmarket and in the Apple Watch app at GlobalLogic, and GCD and OperationQueue at Drinkit.
LLM responses in the app
On the Apple Watch assistant at GlobalLogic, agreed the JSON output format with the AI team and turned structured replies into navigation, warnings, questions and haptics.
Background work
Background URLSession transfers, BGTaskScheduler refresh tasks, silent pushes for order status, and beginBackgroundTask to finish cart work, at Drinkit and Birmarket.
How I work in a team
My part in the team and its processes.
Agile feature teams
Scrum and Kanban in feature teams with product owners, business analysts, backend engineers and QA, with one release per two-week sprint at Birmarket.
Work with product
A/B tests, feature flags and remote configuration with product. Tests took the subscription onboarding from five screens down to three.
Code review and onboarding
Reviewed code in every team and onboarded two iOS engineers into the Birmarket loyalty codebase, usually within one or two sprints.
Planning and decomposition
On large features shared by several engineers, took part in decomposition meetings, proposed technical solutions and agreed how to divide the work.
Joining as a team
Joined Drinkit with an existing mobile team of three iOS and two Android engineers.
Releases and on-call
App Store releases, signing and App Review, the release CI pipeline at Drinkit, and Crashlytics on-call shifts at Birmarket.
Documentation and handover
Documented the subscription SDK and handed it over to a new developer while it was live in three apps.
Skills
- iOS
- Swift
- SwiftUI
- UIKit
- Objective-C
- Swift Concurrency (async/await)
- Combine
- MVVM
- Clean Architecture
- Modular Architecture
- SDK Development
- REST APIs
- Performance Optimization
- Apple frameworks
- StoreKit 2
- CloudKit
- Core Data
- WidgetKit
- App Intents
- Live Activities
- CarPlay
- watchOS
- MapKit
- Core Location
- Apple Foundation Models
- Testing, CI/CD & Release
- XCTest
- Swift Testing
- Unit Testing
- Integration Testing
- Xcode Instruments
- CI/CD
- GitLab CI
- Bitrise
- GitHub Actions
- TestFlight
- App Store Connect
- A/B Testing
- Feature Flags
- Firebase
- PostHog
- Agentic development
- Claude Code
- Codex
