After months of hard work from hundreds of contributors, the React Native Core team is proud to announce the release of version 0.60. This release handles significant migrations for both Android and iOS platforms, and many issues are resolved too. This blog post covers the highlights of the release. As always though, refer to the changelog for more detailed information. Finally, thank you contributors for helping us to make this milestone!

Focus on Accessibility​

There have been many improvements to the accessibility APIs, like announceForAccessibility, plus improvements to roles, action support, flags, and more. Accessibility is a complex science, but we hope these improvements make it a bit easier to be an A11Y. Be sure to check React Native Open Source Update June 2019 for more details of these changes.

A Fresh Start​

React Native's start screen has been updated! Thank you to the many contributors who helped create the new UI. This new "Hello World" will welcome users to the ecosystem in a more friendly, engaging way.

AndroidX Support​

AndroidX is a major step forward in the Android ecosystem, and the old support library artifacts are being deprecated. For 0.60, React Native has been migrated over to AndroidX. This is a breaking change, and your native code and dependencies will need to be migrated as well.

With this change, React Native apps will need to begin using AndroidX themselves. They cannot be used side-by-side in one app, so all of the app code and dependency code needs to be using one or the other.

matt-oakes on discussions-and-proposals

While your own native code will need to be migrated by you, @mikehardy, @cawfree, and @m4tt72 built a clever tool named "jetifier" to patch your node_modules . Library maintainers will need to upgrade, but this tool provide you with a temporary solution while giving them time to release an AndroidX version. So if you find errors related to AndroidX migration, give this a shot.

CocoaPods by Default​

CocoaPods are now part of React Native's iOS project. If you weren't already, be sure to open iOS platform code using the xcworkspace file from now on (protip: try xed ios from the root project directory). Also, the podspec s for the internal packages have changed to make them compatible with the Xcode projects, which will help with troubleshooting and debugging. Expect to make some straightforward changes to your Podfile as part of the upgrade to 0.60 to bring this exciting support. Note that we are aware of a compatibility issue with use_frameworks! , and we're tracking an issue with workarounds and a future patch.

Lean Core Removals​

WebView and NetInfo were previously extracted into separate repositories, and in 0.60 we’ve finished migrating them out of the React Native repository. Additionally, in response to community feedback about new App Store policy, Geolocation has been extracted. If you haven’t already, complete your migration by adding dependencies to react-native-webview, @react-native-community/netinfo, and @react-native-community/geolocation. If you'd like an automated solution, consider using rn-upgrade-deprecated-modules. Maintainers have made more than 100 commits to these repositories since extraction and we’re excited to see the community’s support!

Native Modules are now Autolinked​

The team working on the React Native CLI has introduced major improvements to native module linking called autolinking! Most scenarios will not require the use of react-native link anymore. At the same time, the team overhauled the linking process in general. Be sure to react-native unlink any preexisting dependencies as mentioned in the docs above.

Upgrade Helper​

@lucasbento, @pvinis, @kelset, and @watadarkstar have built a great tool called Upgrade Helper to make the upgrade process simpler. It helps React Native users with brownfield apps or complex customizations to see what's changed between versions. Take a look at the updated upgrading docs and try it out today for your upgrade path!

A Note to Library Maintainers​

Changes for AndroidX will almost certainly require updates to your library, so be sure to include support soon. If you're not able to upgrade yet, consider checking your library against the jetifier to confirm that users are able to patch your library at build time.

Review the autolinking docs to update your configs and readme. Depending on how your library was previously integrated, you may also need to make some additional changes. Check the dependencies guide from the CLI for information on how to define your dependency interface.

Thanks​

While these are the highlights that we noted, there are many others to be excited about. To see all the updates, take a look at the changelog. As always, stay tuned for more news. Enjoy 0.60 in the meantime!

Last week at Chain React we announced Hermes, an open source JavaScript engine we’ve been working on at Facebook. It’s a small and lightweight JavaScript engine optimized for running React Native on Android. Check it out!

Hermes improves React Native performance by decreasing memory utilization, reducing download size, and decreasing the time it takes for the app to become usable or “time to interactive” (TTI).

“As we analyzed performance data, we noticed that the JavaScript engine itself was a significant factor in startup performance and download size. With this data in hand, we knew we had to optimize JavaScript performance in the more constrained environments of a mobile phone compared with a desktop or laptop. After exploring other options, we built a new JavaScript engine we call Hermes. It is designed to improve app performance, focusing on our React Native apps, even on mass-market devices with limited memory, slow storage, and reduced computing power.” —Hermes: An open source JavaScript engine optimized for mobile apps, starting with React Native

Want to get started right away? Be sure to check out our new guide to enabling Hermes in your existing React Native app in the docs!

Illustration by Rachel Nabors

We’re excited to announce React Native 0.61, which includes a new reloading experience we’re calling Fast Refresh.

Fast Refresh​

When we asked the React Native community about common pain points, one of the top answers was that the “hot reloading” feature was broken. It didn’t work reliably for function components, often failed to update the screen, and wasn’t resilient to typos and mistakes. We heard that most people turned it off because it was too unreliable.

In React Native 0.61, we’re unifying the existing “live reloading” (reload on save) and “hot reloading” features into a single new feature called “Fast Refresh” . Fast Refresh was implemented from scratch with the following principles:

• Fast Refresh fully supports modern React , including function components and Hooks.
• Fast Refresh gracefully recovers after typos and other mistakes, and falls back to a full reload when needed.
• Fast Refresh doesn’t perform invasive code transformations so it’s reliable enough to be on by default.

To see Fast Refresh in action, check out this video:

Give it a try, and let us know what you think! If you prefer, you can turn it off in the Dev Menu (Cmd+D on iOS, Cmd+M or Ctrl+M on Android). Turning it on and off is instant so you can do it any time.

Here are a few Fast Refresh tips:

• Fast Refresh preserves React local state in function components (and Hooks!) by default.
• If you need to reset the React state on every edit, you can add a special // @refresh reset comment to the file with that component.
• Fast Refresh always remounts class components without preserving state. This ensures it works reliably.
• We all make mistakes in the code! Fast Refresh automatically retries rendering after you save a file. You don't need to reload the app manually after fixing a syntax or a runtime error.
• Adding a console.log or a debugger statement during edits is a neat debugging technique.

Please report any issues with Fast Refresh on GitHub, and we’ll look into them.

Other Improvements​

• Fixed use_frameworks! CocoaPods support. In 0.60 we made some updates to integrate CocoaPods by default. Unfortunately, this broke builds using use_frameworks!. This is fixed in 0.61, making it easier to integrate React Native into your iOS projects that require building with dynamic frameworks.
• Add useWindowDimensions Hook. This new Hook automatically provides and subscribes to dimension updates, and can be used instead of the Dimensions API in most cases.
• React was upgraded to 16.9. This version deprecates old names for the UNSAFE _ lifecycle methods, contains improvements to act , and more. See the React 16.9 blog post for an automated migration script and more information.

Breaking Changes​

• Remove React .xcodeproj. In 0.60, we introduced auto-linking support via CocoaPods. We have also integrated CocoaPods into the e2e tests runs, so that from now on, we have a unified standard way of integrating RN into iOS apps. This effectively deprecates the React .xcodeproj support, and the file has been removed starting 0.61. Note: if you use 0.60 auto-linking already, you shouldn't be affected.

Thanks​

Thanks to all of the contributors that helped make 0.61 possible!

To see all the updates, take a look at the 0.61 changelog.

After over 20 pull requests from 6 contributors in the React Native Community, we're excited to launch react-native doctor , a new command to help you out with getting started, troubleshooting and automatically fixing errors with your development environment. The doctor command is heavily inspired by Expo and Homebrew's own doctor command with a pinch of UI inspired by Jest.

Here it is in action:

How it works​

The doctor command currently supports most of the software and libraries that React Native relies on, such as CocoaPods, Xcode and Android SDK. With doctor we'll find issues with your development environment and give you the option to automatically fix them. If doctor is not able to fix an issue, it will display a message and a helpful link explaining how to fix it manually as the following:

Try it now​

The doctor command is available as a part of React Native 0.62. However, you can try it without upgrading yet:

npx @react-native-community/cli doctor

What checks are currently supported​

doctor currently supports the following checks:

• Node.js (>= 8.3)
• yarn (>= 1.10)
• npm (>= 4)
• Watchman (>= 4), used for watching changes in the filesystem when in development mode.

Specific to the Android environment:

• Android SDK (>= 26), the software runtime for Android.
• Android NDK (>= 19), the native development toolkit for Android.
• ANDROID_HOME , environment variable required by the Android SDK setup.

And to the iOS environment:

• Xcode (>= 10), IDE for developing, building and shipping iOS applications.
• CocoaPods, library dependency management tool for iOS applications.
• ios-deploy (optional), library used internally by the CLI to install applications on a physical iOS device.

Thanks​

Huge thanks for the React Native Community for working on this, in particular @thymikee, @thib92, @jmeistrich, @tido64 and @rickhanlonii.

Today we’re releasing React Native version 0.62 which includes support for Flipper by default.

This release comes in the midst of a global pandemic. We’re releasing this version today to respect the work of hundreds of contributors who made this release possible and to prevent the release from falling too far behind master. Please be mindful of the reduced capacity of contributors to help with issues and prepare to delay upgrading if necessary.

Flipper by default​

Flipper is a developer tool for debugging mobile apps. It’s popular in the Android and iOS communities, and in this release we’ve enabled support by default for new and existing React Native apps.

Flipper provides the following features out of the box:

• Metro Actions : Reload the app and trigger the Dev Menu right from the toolbar.
• Crash Reporter : View crash reports from Android and iOS devices.
• React DevTools : Use the newest version of React DevTools right alongside all your other tools.
• Network Inspector : View all of the network requests made by device applications.
• Metro and Device Logs : View, search, and filter all logs from both Metro and the Device.
• Native Layout Inspector : View and edit the native layout output by the React Native renderer.
• Database and Preference Inspectors : View and edit the device databases and preferences.

Additionally, since Flipper is an extensible platform, it provides a marketplace that pulls plugins from NPM so you can publish and install custom plugins specific to your workflows. See the available plugins here.

For more information, check out the Flipper documentation.

New dark mode features​

We’ve added a new Appearance module to provide access to the user's appearance preferences, such as their preferred color scheme (light or dark).

const colorScheme = Appearance.getColorScheme();
if (colorScheme === 'dark') {
  // Use dark color scheme
}

We’ve also added a hook to subscribe to state updates to the users preferences:

import {Text, useColorScheme} from 'react-native';

const MyComponent = () => {
  const colorScheme = useColorScheme();
  return <Text>useColorScheme(): {colorScheme}</Text>;
};

See the docs for Appearance and useColorScheme for more information.

Moving Apple TV to react-native-tvos​

As part of our Lean Core effort and to bring Apple TV in line with other platforms like React Native Windows and React Native macOS, we’ve started to remove Apple TV specific code from core.

Going forward, Apple TV support for React Native will be maintained in react-native-community/react-native-tvos along with the corresponding react-native-tvos NPM package. This is a full fork of the main repository, with only the changes needed to support Apple TV.

Releases of react-native-tvos will be based on the public release of React Native. For this 0.62 release of react-native please upgrade Apple TV projects to use react-native-tvos 0.62.

More upgrade support​

When 0.61 was released, the community introduced a new upgrade helper tool to support developers upgrading to new versions of React Native. The upgrade helper provides a diff of changes from the version you're on to the version you're targeting, allowing you to see the changes that need to be made for your specific upgrade.

Even with this tool, issues come up when upgrading. Today we're introducing more dedicated upgrading support by announcing Upgrade-Support. Upgrade Support is a GitHub issue tracker where users can submit issues specific to upgrading their projects to receive help from the community.

We're always working to improve the upgrade experience, and we hope that these tools give users the support they need in the edge cases we haven't covered yet.

Other improvements​

• LogBox : We’re adding the new LogBox error and warning experience as an opt-in; to enable it, add require('react-native').unstable_enableLogBox() to your index.js file.
• React DevTools v4 : This change includes an upgrade to the latest React DevTools which offers significant performance gains, an improved navigation experience, and full support for React Hooks.
• Accessibility improvements : We’ve made improvements to accessibility including adding accessibilityValue, missing props on Touchables, onSlidingComplete accessibility events, and changing the default role of Switch component from "button" to "switch" .

Breaking changes​

• Remove PropTypes : We're removing propTypes from core components in order to reduce the app size impact of React Native core and to favor static type systems which check at compile time instead of runtime.
• Remove accessibilityStates : We’ve removed the deprecated accessibilityStates property in favor of the new accessibilityState prop which is a more semantically rich way for components to describe information about their state to accessibility services.
• TextInput changes : We removed onTextInput from TextInput as it’s uncommon, not W3C compliant, and difficult to implement in Fabric. We also removed the undocumented inputView prop, and selectionState .

Deprecations​

• AccessibilityInfo.fetch was already deprecated, but in this release we added a warning.
• Setting useNativeDriver is now required to support switching the default in the future.
• The ref of an Animated component is now the internal component and deprecated getNode .

Thanks​

Thank you to the hundreds of contributors that helped make 0.62 possible!

To see all the updates, take a look at the 0.62 changelog.