Senior iOS Engineer

About the Role

We operate a mature mobile application targeting global markets, built primarily on a Flutter + native iOS/Android hybrid architecture.

Our current technical focus is continuously enhancing application performance and stability, with a strong emphasis on delivering a smooth experience on older, low-memory iPhones under complex usage scenarios. In this role, you will work across both the shared Flutter layer and the native iOS layer to tackle real-world challenges related to UI jank, memory footprint, startup time, battery consumption, and hybrid architecture interactions.

Key Responsibilities

• Performance Governance: Lead performance optimization for our Flutter & iOS hybrid app, continuously improving startup time, frame rates, memory efficiency, energy consumption, and overall stability.
• Deep Troubleshooting: Diagnose and resolve main thread blocking, frame drops, memory leaks, abnormal memory growth, system memory terminations (Jetsam), and crashes, prioritizing UX improvements for legacy devices.
• Flutter Rendering Optimization: Optimize Flutter widget building, layout, and rendering pipelines—resolving issues caused by unnecessary rebuilds, image decoding/caching, long scrollable lists, animations, and asynchronous tasks.
• Hybrid Integration & Interop: Streamline integration between Flutter and native iOS pages, Platform Views, platform channel communications, and 3rd-party SDKs, addressing thread scheduling, object retention, and resource cleanup.
• Metrics & Regression Control: Establish production performance metrics, device/OS version stratified analysis, and regression testing mechanisms, validating optimization gains on physical devices.
• Cross-Functional Collaboration: Partner with Android, QA, and product engineering teams to drive shared Flutter layer optimizations, manage platform-specific differences, and lower performance regression risks.

Key Requirements

• Experience: 5+ years of mobile development experience with a strong foundation in native iOS, alongside hands-on production experience with Flutter development and performance optimization.
• Core Tech Stack: Proficient in Swift/Objective-C and Dart, with a deep understanding of ARC, RunLoop, GCD, thread synchronization, rendering pipelines, and the iOS application lifecycle.
• Flutter Internal Mechanics: Solid grasp of the Widget, Element, and RenderObject hierarchy, UI/Raster threads, Event Loops, Isolates, and Platform Channel mechanics.
• Profiling & Diagnostics: Proficient with Xcode Instruments (Time Profiler, Allocations, Leaks), Xcode Memory Graph, and Flutter DevTools for precise performance bottleneck identification.
• iOS System Architecture: Deep understanding of iOS memory pressure, background execution, and system termination mechanisms, with the ability to combine device logs and production telemetry for root-cause analysis.
• Track Record: Proven history of successful production performance optimizations, with the ability to clearly articulate problem contexts, diagnostic processes, implemented solutions, quantified gains, and regression validation protocols.
• Cross-Layer Debugging: Strong capability to determine whether bottlenecks originate from Dart, Flutter rendering, native iOS modules, 3rd-party SDKs, or OS resource limits.
• Execution & Ownership: Ability to independently drive optimization initiatives in a mature codebase while balancing technical ROI, compatibility, and release risks.

Preferred Qualifications (Nice to Have)

• Experience with performance governance for legacy iPhone models, low-memory devices, and multi-version iOS environments.
• Hands-on optimization experience in high-demand scenarios such as audio/video, real-time communication (RTC), complex animations, or high-frequency image rendering.
• Familiarity with C/C++, Flutter Engine internals, Impeller, Metal, or graphics rendering technologies.
• Experience with MetricKit, APM/production jank monitoring systems, performance metrics frameworks, or automated performance testing pipelines.

Remarks: This role is currently on a hybrid arrangement. However, employees may be required to return to the office on a full on-site basis in the future, subject to company policy.