Yoshimasa Niwa
Software Engineer at Twitter Inc
Summary
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RockstarYoshimasa Niwa is a seasoned software engineer with 18 years of experience building reliable, low-level and user-facing systems across iOS, macOS, and Swift core libraries. He contributes to notable open-source projects—improving Twitter’s iOS rich text editor, hardening Swift Foundation file-write semantics, and optimizing the Swift ANTLR4 runtime—demonstrating expertise in performance-sensitive refactors and cross-platform correctness. Comfortable across Objective-C, Swift, and system libraries, he pairs bug fixes and tests with API improvements and documentation to raise maintainability. A pragmatic full-stack thinker, he also builds small, user-focused tools like a Touch Bar haptic utility and cares about accessibility and UX details. Less obvious: he blends attention to developer experience (type clarity, unit tests) with end-user polish, making him effective at both library internals and app-level interactions.
18 years of coding experience
Github Skills (18)
textkit10
unit-testing10
objective-c10
ios10
mobile-development10
event-handling10
foundation10
parsing10
antlr10
file-handling10
swift10
uikit10
macos10
text-parsing10
ui-design9
Programming languages (15)
Github contributions (5)
niw/HapticKey
Dec 2017 - Nov 2021
A simple utility application to trigger haptic feedback when tapping Touch Bar.
Role in this project:
Full-stack Developer
Full-stack DeveloperContributions:17 releases, 3 reviews, 181 commits in 3 years 11 months
Contributions summary:Yoshimasa primarily worked on the application's core functionality and user interface, focusing on Objective-C and macOS development. They refactored code, renaming classes and updating methods to improve code quality and maintainability. The user also introduced new features and refactored the code to incorporate an event-driven architecture, allowing the application to respond to user interactions with the Touch Bar. The user also addressed accessibility issues by adding keyboard shortcuts.
objective-chaptichaptic-feedbacktriggertouch
twitter/TwitterTextEditor
Jun 2020 - Jan 2023
A standalone, flexible API that provides a full-featured rich text editor for iOS applications.
Role in this project:Mobile Developer (iOS)
Mobile Developer (iOS)Contributions:7 reviews, 26 commits, 8 PRs in 2 years 6 months
Contributions summary:Yoshimasa primarily contributed to the `TwitterTextEditor` project, focusing on iOS-specific development. Their work included adding and modifying Swift code, particularly within `TextEditorView` and related files. They implemented features such as `returnToEndEditingEnabled`, updated UIResponder methods, and addressed bugs related to text input behavior and pasting. The user also updated documentation and refactored code to leverage new Swift features.
apifull-featuredrich-text-editorrich-textstandalone
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