Kaifeng S.

🚀 Staff iOS Engineer (10+ yrs) — Real-time Video/VoIP & AI Integration I build and fix iOS/macOS apps fast—clean, stable, and ready to ship. Previously at Fanatics (Live & Collect), Agora (macOS Tech Lead), and RingCentral (Staff Engineer). I specialize in two high-value areas: real-time audio/video systems and production AI integration. ✅ Selected impact • Reduced crash rate 10x through systematic stability work (crash/ANR triage, threading, memory) • Improved user NPS +40% via closed-loop quality optimization • Evolved a live platform from viewer-only → full broadcaster (streaming + interactions) • Built ANR monitoring (main-thread blocking detection) → 3x faster issue resolution • Experience shipping for massive-scale consumer products (e.g., bilibili-level traffic) 🎥 Real-time audio/video & streaming (production) • Live streaming & video conferencing: LiveKit / Agora SDK / Amazon IVS • AVFoundation capture/render pipelines, recording/upload, performance tuning • CallKit + PushKit VoIP calling (background, reconnect, audio routes, reliability) • Real-time interactions: auctions, voting, chat (WebSocket / GraphQL Subscriptions) • Screen sharing: iOS App Extension + macOS plugins • Socket/IM architecture experience; solid networking fundamentals (TCP/UDP) 🤖 AI integration • OpenAI / Claude API integration for user-facing features • HealthKit + Apple Watch data pipelines (sleep/HR/activity/workouts) • Prompt & context management, on-device + cloud orchestration for personalized insights 🏗️ Architecture & engineering • Clean Architecture / SOLID, protocol-oriented DI, modular design • TCA & MVVM (migration and coexistence), Swift Concurrency (async/await, Actors) • Swift + Objective-C, pragmatic refactors, long-term maintainability 🧪 Quality & delivery • Tests: XCTest/XCUITest, snapshot tests; TDD when valuable (Quick/Nimble) • CI/CD: Fastlane, Jenkins/GitHub Actions/Xcode Cloud, TestFlight/App Store release • Logging/analytics (e.g., Firebase/Crashlytics) to locate root causes quickly 🛠️ How I work • Start with a short paid assessment → confirm scope, estimate, and risks • Milestones with demos + clear acceptance criteria • Strong communication, pragmatic testing, and maintainable Swift • Available 40 hrs/week, fluent in English, timezone-friendly and responsive 💻 Equipment: Mac Studio (M1 Max, 32GB), dual 28” 4K monitors, 1Gbps fiber. If you’re building live video/VoIP features, integrating AI into an app, or need to stabilize and scale an existing codebase, feel free to message me—happy to review your scope and propose a plan.