React Native Blog • Mar 12, 2021

React Native 0.64 Release

Article Summary

React Native 0.64 just brought Hermes to iOS, and it's a game-changer for app performance. The team is finally closing the gap between Android and iOS optimization.

The React Native team released version 0.64 with major performance improvements across both platforms. This release focuses on reducing app startup time, memory usage, and download size through engine optimizations and smarter module loading.

Key Takeaways

Hermes engine now available on iOS, reducing memory and improving time to interactive
Inline Requires enabled by default, delaying module execution until needed
Hermes adds Proxy support, unlocking compatibility with Firebase and MobX
Chrome DevTools integration lets you visualize Hermes performance traces
React 17 included with new JSX transform (no more importing React)

Critical Insight

React Native 0.64 delivers cross-platform Hermes support and automatic startup optimizations that make apps faster without extra configuration.

The team hints that Hermes will become the default Android engine soon, but there's a specific reason they're keeping iOS opt-in for now.

About This Article

Problem

React Native dropped support for Android API levels 16-20 after Facebook stopped supporting these versions. Developers now need to update their minimum Android requirements.

Solution

The React Native team updated their dependencies. Xcode was bumped to version 12, CocoaPods to 1.10, and Node support moved from 10 to 12. Flipper was also upgraded to 0.75.1.

Impact

Developers using Hermes can now view application execution in Chrome DevTools' Performance tab. This work came from MLH fellowship members Jessie Nguyen and Saphal Patro.