Summary
Senior iOS Engineer with 14 years of production experience. Ranked #1 iOS & Swift mentor globally on Codementor with 2000+ sessions and a 5.0/5 rating - a publicly verifiable track record of solving the hardest iOS problems across 1000+ client codebases. Delivered measurable product impact - 95% trial-to-paid conversion improvement and 37% onboarding drop-off reduction at Fext.
Specialized in architecting scalable iOS systems, SDKs, and data-intensive applications, particularly in HealthTech and AI-driven products. Known for rapidly diagnosing and resolving complex production issues across diverse codebases.
Technical Skills
Languages
Swift, Objective-C, JavaScript (ES6+), HTML5, CSS3
Frameworks
SwiftUI, UIKit, WatchKit, Combine, CoreData, HealthKit, CareKit, ResearchKit, CloudKit, AVFoundation, Core Bluetooth, Node.js
Architecture
MVC, MVVM, Clean Architecture (VIPER), Modular Systems, SOLID Principles, Offline-first, HIPAA/GDPR Compliance
Tools & APIs
Xcode, Git, Fastlane, GitHub Actions, Bitrise, Jenkins, REST, SOAP, WebSockets, JSON, XML, OAuth, Stripe
Experience
iOS Expert (Consultant) —
Codementor
2015 – Present
- Delivered 2000+ paid 1:1 mentoring sessions (typically 60 min) with a 5.0/5 rating across 1000+ clients.
- Resolved 1–2 production issues per hour-long session on average, spanning performance, architecture, concurrency, and debugging of complex iOS systems.
- Maintained under 10 minute response time during peak availability and achieved over 99.5% issue resolution rate. Majority repeat clients (over 80%), reflecting high trust and effectiveness.
Full Stack Engineer (iOS + Node.js) —
Fext
2024 – 2025
- Increased trial-to-paid conversion by 95% and reduced onboarding drop-off by 37% for a SMS marketing platform for small businesses, through targeted UX and core user flow optimizations.
- Designed and built the full stack from scratch and then implemented a pivot away from Twilio (due to regulatory changes). Redesigned user flows (on-device delivery) using Swift and UIKit, improving usability and conversions.
- Helped to focus down the scope - saved 4 weeks of development. Provided extensive support after delivery.
- Integrated Firebase, Twilio, and RevenueCat, implemented text scheduling and delivery on the backend (Node.js).
iOS Engineer (SDK & Infrastructure) —
Intelligent Business Platforms
2022 – 2024
- Architected and built an AI-powered iOS application using SwiftUI and structured concurrency, focused on real-time data processing and scalable workflows.
- Developed and maintained a Swift SDK for BigParser, enabling efficient integration with large-scale tabular data systems. Open source, available at: github.com/intellibus/bigparser-swift
- Engineered complex data pipelines integrating Whisper API, ChatGPT API, AWS services, and BigParser - including streaming, transcription, and automated summarization workflows.
- Built robust networking layer with background task orchestration, upload/download managers, and resilient session handling for long-running operations.
iOS Engineer —
Brigham and Women’s Hospital
2021 – 2022
- Spearheaded the development of new UI/UX features in SwiftUI for the SPARKLE clinical research application, enhancing user engagement and accessibility for residents in the Medicine and Surgery programs.
- Optimized data handling and state management across complex UI flows, implementing a robust record caching system and refactoring API usage, which significantly improved application responsiveness and data consistency.
- Collaborated directly with clinicians and product teams at a Harvard-affiliated institution to integrate critical research and education-focused features.
Senior iOS/watchOS Engineer (SDK & Infrastructure) —
Hippocrates Technologies (TheraForge)
2019 – 2021
- Architected and engineered the TheraForge SDK ecosystem (open source, available at github.com/TheraForge), a reusable HealthTech framework adopted by enterprise partners (including Tec4med and Middle East College) to accelerate FDA-grade digital health application development.
- Developed OTFCDTDatastore, an offline-first NoSQL storage engine based on IBM Cloudant. Implemented AES-256 encryption-at-rest and granular iOS File Protection levels to ensure HIPAA/GDPR compliance.
- Engineered OTFCloudantStore, a high-performance integration layer bridging Apple HealthKit, CareKit, and ResearchKit with the IBM Cloudant sync engine, enabling seamless multi-device synchronization of complex health datasets.
- Optimized background processing for continuous health data ingestion, implementing synchronization while adhering to strict iOS background execution limits and power management constraints.
- Built OTFCloudClientAPI, a robust RESTful interface supporting secure authentication, Server-Sent Events (SSE) for real-time updates, and end-to-end encrypted document management.
- Maintained enterprise-grade forks of Apple’s CareKit and ResearchKit, extending them with custom aggregators, query parameters, and watchOS support to meet the requirements of large-scale clinical research and remote patient monitoring initiatives.
Senior iOS/watchOS Developer —
Proactive Life, Inc.
2018 – 2019
- Made a comprehensive refactoring of the core iOS codebase from Objective-C to Swift, significantly enhancing application performance, maintainability, and stability for future feature development.
- Implemented sophisticated noise cancellation algorithms based on clinical research, improving user sleep quality and solidifying the app’s position as a leading sleep therapy solution. Collaborated closely with PhD researchers on the team to translate research models into production-ready code.
- Built the watchOS app from scratch and implemented a battery-efficient night-long sleep tracking (using the built-in sensors) background synchronization protocol between Apple Watch and iPhone — enabled continuous overnight operation on watchOS while minimizing battery impact. Improved battery life from 2 hours to 8 hours.
- Implemented real-time dynamic sound masking and integrated ML backend-driven therapeutic audio playback and routing system.
- Significantly contributed to the app’s recognition for accurate sleep tracking validated by NIH grants.
iOS Developer —
Multiple Startups & Agencies
2011 – 2018
- Worked across Sports Analytics, Movez, Avial, WDF, Forbidd, Crazy Tomato, IMPER CZ, and others.
- Delivered mobile applications, backend integrations, and early-stage products.
Education
Bachelor’s Degree in Software Engineering —
Czech Technical University in Prague
Languages
English — C2 (Fluent)
Czech — Native
Slovak — Professional
German — A2 (Elementary)