Mobile Development 5 min read

Optimizing Flutter Engine for 120 Hz on iPhone 13 – Internship Experience

During a three‑month internship at Xianyu, senior software engineering student Wen Jingrui (Mu Chen) tackled Flutter Engine limitations on the iPhone 13’s 120 Hz display, debugging iOS frame‑callback code to enable smooth rendering, fixing keyboard‑animation bugs, and contributing video and image editor features, ultimately earning a full‑time offer.

Xianyu Technology
Xianyu Technology
Xianyu Technology
Optimizing Flutter Engine for 120 Hz on iPhone 13 – Internship Experience

Author: Wen Jingrui (nickname Mu Chen), GitHub: luckysmg , a senior software engineering student at Harbin Institute of Technology who interned at Xianyu’s tech team for three months, focusing on Flutter Engine optimization for video and image editors.

Initially shocked by the massive codebase and half‑hour compile times, he quickly learned Flutter after a native‑only background and familiarized himself with the project’s modular structure.

He contributed to two core publishing pages—video editor and image editor—handling strong user interactions; the image editor required geometric transformations using vector dot and cross products.

He discovered that iPhone 13’s 120 Hz high‑refresh display was not supported by the Flutter iOS engine, causing stutter. By debugging and modifying the iOS frame‑callback code in the Flutter Engine , he enabled smooth 120 Hz rendering.

He also fixed a missing keyboard‑animation issue on iOS by adjusting engine code, improving overall user experience.

The three‑month internship significantly boosted his technical skills, earned him a full‑time offer, and highlighted the team’s collaborative atmosphere.

FlutterMobile DevelopmentiOSinternshipengine optimizationhigh refresh rate
Xianyu Technology
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