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Hi, I’m Kaifeng, a Staff iOS/macOS Engineer with ten years of experience. I’ve been focusing on building scalable, high-performance iOS applications, particularly in real-time social apps and cross-platform architecture. at Fanatics, I served as Staff iOS Engineer responsible for core feature development of Live streaming app and Collect auction app. I implemented of Live's complete streaming system and chat system and Collect's auction extend bidding hybrid architecture. At RingCentral, I served as Staff Staff iOS Engineer, I designed and implemented real-time translation components for meetings, as well as a cross-platform ANR monitoring system that significantly improved our ANR issue resolution rate. At Agora, I worked as Tech Lead for AgoraVideoCall iOS and macOS meeting app development, focusing on core features like screen sharing, chat VoIP, and room video management. I led the team through an architectural migration from MVC to MVVM and reduced our iOS crash rate from 0.3% to 0.04%. These ten years have given me deep expertise in iOS/macOS development, real-time system architecture, and technical leadership. I'm excited about the opportunity to bring this experience to a new platform.…Hi, I’m Kaifeng, a Staff iOS/macOS Engineer with ten years of experience. I’ve been focusing on building scalable, high-performance iOS applications, particularly in real-time social apps and cross-platform architecture. at Fanatics, I served as Staff iOS Engineer responsible for core feature development of Live streaming app and Collect auction app. I implemented of Live's complete streaming system and chat system and Collect's auction extend bidding hybrid architecture. At RingCentral, I served as Staff Staff iOS Engineer, I designed and implemented real-time translation components for meetings, as well as a cross-platform ANR monitoring system that significantly improved our ANR issue resolution rate. At Agora, I worked as Tech Lead for AgoraVideoCall iOS and macOS meeting app development, focusing on core features like screen sharing, chat VoIP, and room video management. I led the team through an architectural migration from MVC to MVVM and reduced our iOS crash rate from 0.3% to 0.04%. These ten years have given me deep expertise in iOS/macOS development, real-time system architecture, and technical leadership. I'm excited about the opportunity to bring this experience to a new platform.

Kaifeng Sun

App Developer, Web Developer, Full Stack Developer, +7

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Hi, I’m Kaifeng, a Staff iOS/macOS Engineer with ten years of experience. I’ve been focusing on building scalable, high-performance iOS applications, particularly in real-time social apps and cross-platform architecture. at Fanatics, I served as Staff iOS Engineer responsible for core feature development of Live streaming app and Collect auction app. I implemented of Live's complete streaming system and chat system and Collect's auction extend bidding hybrid architecture. At RingCentral, I served as Staff Staff iOS Engineer, I designed and implemented real-time translation components for meetings, as well as a cross-platform ANR monitoring system that significantly improved our ANR issue resolution rate. At Agora, I worked as Tech Lead for AgoraVideoCall iOS and macOS meeting app development, focusing on core features like screen sharing, chat VoIP, and room video management. I led the team through an architectural migration from MVC to MVVM and reduced our iOS crash rate from 0.3% to 0.04%. These ten years have given me deep expertise in iOS/macOS development, real-time system architecture, and technical leadership. I'm excited about the opportunity to bring this experience to a new platform.…Hi, I’m Kaifeng, a Staff iOS/macOS Engineer with ten years of experience. I’ve been focusing on building scalable, high-performance iOS applications, particularly in real-time social apps and cross-platform architecture. at Fanatics, I served as Staff iOS Engineer responsible for core feature development of Live streaming app and Collect auction app. I implemented of Live's complete streaming system and chat system and Collect's auction extend bidding hybrid architecture. At RingCentral, I served as Staff Staff iOS Engineer, I designed and implemented real-time translation components for meetings, as well as a cross-platform ANR monitoring system that significantly improved our ANR issue resolution rate. At Agora, I worked as Tech Lead for AgoraVideoCall iOS and macOS meeting app development, focusing on core features like screen sharing, chat VoIP, and room video management. I led the team through an architectural migration from MVC to MVVM and reduced our iOS crash rate from 0.3% to 0.04%. These ten years have given me deep expertise in iOS/macOS development, real-time system architecture, and technical leadership. I'm excited about the opportunity to bring this experience to a new platform.

Available to hire

Hi, I’m Kaifeng, a Staff iOS/macOS Engineer with ten years of experience. I’ve been focusing on building scalable, high-performance iOS applications, particularly in real-time social apps and cross-platform architecture.
at Fanatics, I served as Staff iOS Engineer responsible for core feature development of Live streaming app and Collect auction app. I implemented of Live’s complete streaming system and chat system and Collect’s auction extend bidding hybrid architecture.
At RingCentral, I served as Staff Staff iOS Engineer, I designed and implemented real-time translation components for meetings, as well as a cross-platform ANR monitoring system that significantly improved our ANR issue resolution rate.
At Agora, I worked as Tech Lead for AgoraVideoCall iOS and macOS meeting app development, focusing on core features like screen sharing, chat VoIP, and room video management. I led the team through an architectural migration from MVC to MVVM and reduced our iOS crash rate from 0.3% to 0.04%.
These ten years have given me deep expertise in iOS/macOS development, real-time system architecture, and technical leadership. I’m excited about the opportunity to bring this experience to a new platform.

Skills

Experience Level

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Expert

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Intermediate

Language

English

Fluent

Work Experience

Staff iOS Engineer at Fanatics Live & Fanatics Collect

August 1, 2025 - September 21, 2025

Responsible for the iOS technical strategy and implementation of Fanatics' two core businesses: interactive live auction platform (Live) and trading card marketplace (Collect). Led architectural evolution toward a TCA-based MVVM flow, built a high-concurrency real-time interactive system using WebSocket for live voting, auctions, and giveaways, and implemented a hybrid intelligent long-polling + WebSocket auction architecture with StreamChat-based messaging.

Staff Software Engineer at RingCentral

December 1, 2022 - September 21, 2025

Core contributor for audio/video conferencing on iOS/macOS. Implemented ANR monitoring with real-time main thread tracing, delivering a 300% improvement in ANR issue resolution, and led the real-time captions feature from API design to UI. Built modular cross-platform logic and performance-oriented infrastructure.

Tech Lead - AgoraVideoCall at Agora

January 1, 2022 - September 21, 2025

Led UI/SDK development for AgoraVideoCall apps on iOS/macOS. Designed a modular Swift protocol-based architecture, implemented a cross-platform logging and analytics system to reduce crash rates, and developed screen sharing functionality with AppExtension/Plugins. Built C++ cross-platform SDK with arm64/x86_64 support and runtime ThemeManager.

Senior iOS Engineer at Shanghai Duoqu Technology Co., Ltd.

August 1, 2019 - September 21, 2025

Architected real-time messaging (Socket + Protobuf) with MVVM + RxSwift, including one-to-one/group/chat, chat rooms, and voice communication; implemented robust offline message processing and synchronization.

iOS Engineer at Bilibili

September 1, 2018 - September 21, 2025

Responsible for performance optimization of video player UX and overall user experience during high-load scenarios.

iOS Engineer at Shanghai Shanda Games

May 1, 2018 - September 21, 2025

Led 0-to-1 development of social app "Half Fish - Call Your Other Half" using RxSwift + MVVM and implemented core messaging and voice features.

Senior iOS Engineer at Shanghai Xiangguo Network

May 1, 2017 - September 21, 2025

Developed real-time synchronized writing whiteboard for interactive teaching using XMPP-based messaging and Quartz2D; built reactive MVVM + RxSwift architecture for real-time events.

Senior iOS Engineer at Shanghai Xiangguo Network

May 1, 2017 - September 21, 2025

Real-time synchronized writing whiteboard based on XMPP protocol and Quartz2D; MVVM + RxSwift for real-time collaboration and teaching; extensive offline message processing.

Lead iOS Engineer at Shanghai Shanda Games

May 1, 2018 - September 21, 2025

Led 0-to-1 development of social app "Half Fish - Call Your Other Half" using RxSwift + MVVM; built ChatService module with Huanxin SDK; features included 3D planet and bullet comment views.

Senior iOS Engineer at Bilibili

September 1, 2018 - September 21, 2025

Main Site Technical Center, responsible for performance optimization of video player user experience.

Senior iOS Engineer at Shanghai Duoqu Technology Co., Ltd.

August 1, 2019 - September 21, 2025

Real-Time Messaging Architecture: IM protocol system using Socket and Protobuf; reactive MVVM + RxSwift for real-time messages; optimized synchronization and large-scale offline message processing.

Tech Lead - AgoraVideoCall at Agora

January 1, 2022 - September 21, 2025

Led development for AgoraVideoCall on iOS/macOS; designed modular architecture; implemented comprehensive logging/analytics; reduced crash rates (iOS 0.3%→0.04%, macOS 0.6%→0.03%); implemented screen sharing via AppExtension (iOS) and Plugins (macOS); built cross-platform C++ SDK with wrappers; implemented runtime ThemeManager and PushKit/CallKit VoIP; developed unified cross-platform logic.

Staff Software Engineer at RingCentral

December 1, 2022 - September 21, 2025

Core team member for audio/video conferencing app (Rooms); designed ANR monitoring system enabling main thread blocking capture/reporting; drove 300% improvement in ANR issue resolution; led real-time captions feature including API, real-time processing, and accessible UI components.

Staff iOS Engineer | Product Owner | DRI at Fanatics Live & Fanatics Collect

August 1, 2025 - September 21, 2025

Responsible for the iOS technical strategy and implementation of Fanatics' two core businesses: interactive live auction platform (Live) and trading card marketplace (Collect). Evolved Live to a full interactive live streaming ecosystem; built a high-concurrency real-time system based on WebSocket for live voting, auctions, and giveaways; developed a hybrid 'intelligent long polling + WebSocket' auction architecture to optimize server resources; migrated key modules to TCA; built OfferChatMessageService for real-time buyer-seller messaging via StreamChat; acted as Product Owner/DRI for cross-platform collaboration.

Staff iOS Engineer at Fanatics Live & Fanatics Collect

August 1, 2025 - September 21, 2025

As Staff iOS Engineer and DRI, owned the iOS strategy and implementation for Fanatics' two core businesses: interactive live auction (Live) and trading card marketplace (Collect). Evolved the iOS Live platform from consumption-only to a complete interactive streaming ecosystem with broadcaster–audience interactions. Built a high-concurrency real-time system based on WebSocket to support live voting, auctions, and giveaways. Designed a hybrid auction architecture for Collect using intelligent long polling plus WebSocket to optimize server resources while preserving real-time performance. Migrated key modules to a TCA-based architecture and established best practices for MVVM-TCA coexistence during progressive migration. Developed OfferChatMessageService for Collect to synchronize offers and enable real-time messaging between buyers and sellers via StreamChat-based services. As PO/DRI, participated in cross-platform product decisions to ensure seamless UX across Live and Collect.

Staff Software Engineer at RingCentral

December 1, 2022 - September 21, 2025

Core team member for the iOS/macOS audio/video conferencing app (Rooms). Led ANR monitoring implementation to capture main-thread blocking traces and accelerate stability improvements, achieving a 300% increase in ANR issue resolution. Designed end-to-end real-time captions feature, including API design, real-time speech processing, and accessible UI components, contributing to improved accessibility and user experience across platforms.

Tech Lead - AgoraVideoCall at Agora

January 1, 2022 - September 21, 2025

Led a development team responsible for AgoraVideoCall iOS/macOS apps, guiding full product lifecycle and architectural decisions. Designed a comprehensive logging and analytics system for closed-loop user quality reporting and crash analysis, driving significant crash-rate reductions. Architected a modular application framework using Swift protocol-oriented design with unified cross-platform logic for iOS/macOS through module registration/deregistration patterns and modular podspec architecture. Implemented screen sharing with AppExtension (iOS) and Plugins (macOS), built a cross-platform C++ SDK with a unified business logic layer, and created a runtime ThemeManager for dynamic design resources. Implemented VoIP capabilities via PushKit + CallKit and improved stability and user experience.

Senior iOS Engineer at Shanghai Duoqu Technology Co., Ltd.

August 1, 2019 - September 21, 2025

Real-Time Messaging Architecture: Architected IM protocol system using Socket and Protobuf to support one-on-one chat, group chat, chat rooms, and voice communication. Built reactive MVVM + RxSwift-based architecture for complex real-time event handling and message processing, including robust offline message processing and synchronization.

Main Site Engineer at Bilibili

September 1, 2018 - September 21, 2025

Responsible for performance optimization of the video player user experience at the main site technical center, contributing to stability and smooth playback enhancements.

Lead iOS Engineer at Shanghai Shanda Games

May 1, 2018 - September 21, 2025

Led 0-to-1 development of the social app 'Half Fish - Call Your Other Half' using RxSwift + MVVM. Built message and voice connection ChatService modules using Huanxin SDK, implementing features including a 3D planet view and bullet comments.