Today we are excited to release React Native 0.79!
This release ships with performance improvements on various fronts, as well as several bugfixes. First, Metro is now faster to start thanks to deferred hashing, and has stable support for package exports. Startup time in Android will also be improved thanks to changes in the JS bundle compressions and much more.
Today we are excited to release React Native 0.78!
This release ships React 19 in React Native and some other relevant features like native support for Android Vector drawables and better brownfield integration for iOS.
Every year, the core contributors in the React Native Community get together with the React Native team to collaboratively shape the direction of this project.
Last year was no different—with small exception. We usually meet a day before React Universe Conf (formerly React Native EU) at Callstack HQ in Wrocław. In 2024, learning from past experiences, we hosted the Summit for two consecutive days, so that we can have more unstructured time together.
Today we are excited to release React Native 0.77!
This release ships several features: new styling capabilities such as support for display: contents, boxSizing, mixBlendMode, and outline-related properties to provide a more powerful layout options; Android 16KB page support to be compatible with the newer Android devices. We are also modernizing the community template by migrating it to Swift, while continuing to support and maintain compatibility with Objective-C for developers who prefer it.
Today we are excited to release React Native 0.75!
This release ships several features, such as Yoga 3.1 with support for % values, several stabilization fixes for the New Architecture, and the introduction of the recommendation for users to use a React Native Framework.
Now that 0.71 is available, we want to share some key information about the incident that broke Android builds for all React Native versions while releasing the first 0.71 release candidate for React Native & Expo Android builds on November 4th, 2022.
The contributors who helped tackle the incident recently attended a post-mortem meeting to discuss in detail what happened, what we all learned from it, and what actions we are going to take to avoid similar outages in the future.
With the release of 0.71, React Native is investing in the TypeScript experience with the following changes:
In this post we’ll cover what these changes mean for you as a TypeScript or Flow user.
Hello everyone!
With new mobile OS versions releasing late this year, we recommend preparing your React Native apps beforehand to avoid regressions when the releases become generally available.
For a long time now, Apple has discouraged using UIWebViews in favor of WKWebView. In iOS 12, which will be released in the upcoming months, UIWebViews will be formally deprecated. React Native's iOS WebView implementation relies heavily on the UIWebView class. Therefore, in light of these developments, we've built a new native iOS backend to the WebView React Native component that uses WKWebView.
The tail end of these changes were landed in this commit, and will become available in the 0.57 release.
To opt into this new implementation, please use the useWebKit prop:
<WebView
useWebKit={true}
source={{url: 'https://www.google.com'}}
/>
UIWebView had no legitimate way to facilitate communication between the JavaScript running in the WebView, and React Native. When messages were sent from the WebView, we relied on a hack to deliver them to React Native. Succinctly, we encoded the message data into a url with a special scheme, and navigated the WebView to it. On the native side, we intercepted and cancelled this navigation, parsed the data from the url, and finally called into React Native. This implementation was error prone and insecure. I'm glad to announce that we've leveraged WKWebView features to completely replace it.
Other benefits of WKWebView over UIWebView include faster JavaScript execution, and a multi-process architecture. Please see this 2014 WWDC for more details.
If your components use the following props, then you may experience problems when switching to WKWebView. For the time being, we suggest that you avoid using these props:
Inconsistent behavior:
automaticallyAdjustContentInsets and contentInsets (commit)
When you add contentInsets to a WKWebView, it doesn't change the WKWebView's viewport. The viewport remains the same size as the frame. With UIWebView, the viewport size actually changes (gets smaller, if the content insets are positive).
backgroundColor (commit)
With the new iOS implementation of WebView, there's a chance that your background color will flicker into view if you use this property. Furthermore, WKWebView renders transparent backgrounds differently from UIWebview. Please look at the commit description for more details.
Not supported:
scalesPageToFit (commit)
WKWebView didn't support the scalesPageToFit prop, so we couldn't implement this on the WebView React Native component.
As technology advances and mobile apps become increasingly important to everyday life, the necessity of creating accessible applications has likewise grown in importance.
React Native's limited Accessibility API has always been a huge pain point for developers, so we've made a few updates to the Accessibility API to make it easier to create inclusive mobile applications.
accessibilityComponentType and accessibilityTraits are two properties that are used to tell TalkBack on Android and VoiceOver on iOS what kind of UI element the user is interacting with. The two biggest problems with these properties are that:
accessibilityTraits on iOS allows 17 different values while accessibilityComponentType on Android allows only 4 values. Furthermore, the values for the most part had no overlap. Even the input types for these two properties are different. accessibilityTraits allows either an array of traits to be passed in or a single trait, while accessibilityComponentType allows only a single value.Accessibility Hints help users using TalkBack or VoiceOver understand what will happen when they perform an action on an accessibility element that is not apparent by only the accessibility label. These hints can be turned on and off in the settings panel. Previously, React Native's API did not support accessibility hints at all.
Some users with vision loss use inverted colors on their mobile phones to have greater screen contrast. Apple provided an API for iOS which allows developers to ignore certain views. This way, images and videos aren't distorted when a user has the inverted colors setting on. This API is currently unsupported by React Native.
In order to solve the confusion between accessibilityComponentType and accessibilityTraits, we decided to merge them into a single property. This made sense because they technically had the same intended functionality and by merging them, developers no longer had to worry about platform specific intricacies when building accessibility features.
Background
On iOS, UIAccessibilityTraits is a property that can be set on any NSObject. Each of the 17 traits passed in through the javascript property to native is mapped to a UIAccessibilityTraits element in Objective-C. Traits are each represented by a long int, and every trait that is set is ORed together.
On Android however, AccessibilityComponentType is a concept that was made up by React Native, and doesn't directly map to any properties in Android. Accessibility is handled by an accessibility delegate. Each view has a default accessibility delegate. If you want to customize any accessibility actions, you have to create a new accessibility delegate, override specific methods you want to customize, and then set the accessibility delegate of the view you are handling to be associated with the new delegate. When a developer set AccessibilityComponentType, the native code created a new delegate based off of the component that was passed in, and set the view to have that accessibility delegate.
Changes Made
For our new property, we wanted to create a superset of the two properties. We decided to keep the new property modeled mostly after the existing property accessibilityTraits, since accessibilityTraits has significantly more values. The functionality of Android for these traits would be polyfilled in by modifying the Accessibility Delegate.
There are 17 values of UIAccessibilityTraits that accessibilityTraits on iOS can be set to. However, we didn't include all of them as possible values to our new property. This is because the effect of setting some of these traits is actually not very well known, and many of these values are virtually never used.
The values UIAccessibilityTraits were set to generally took on one of two purposes. They either described a role that UI element had, or they described the state a UI element was in. Most uses of the previous properties we observed usually used one value that represented a role and combined it with either “state selected,” “state disabled,” or both. Therefore, we decided to create two new accessibility properties: accessibilityRole and accessibilityState.
accessibilityRole
The new property, accessibilityRole, is used to tell Talkback or Voiceover the role of a UI Element. This new property can take on one of the following values:
nonebuttonlinksearchimagekeyboardkeytextadjustableheadersummaryimagebuttonThis property only allows one value to be passed in because UI elements generally don't logically take on more than one of these. The exception is image and button, so we've added a role imagebutton that is a combination of both.
accessibilityStates
The new property, accessibilityStates, is used to tell Talkback or Voiceover the state a UI Element is in. This property takes on an Array containing one or both of the following values:
selecteddisabledFor this, we added a new property, accessibilityHint. Setting this property will allow Talkback or Voiceover to recite the hint to users.
accessibilityHint
This property takes in the accessibility hint to be read in the form of a String.
On iOS, setting this property will set the corresponding native property AccessibilityHint on the view. The hint will then be read by Voiceover if Accessibility Hints are turned on in the iPhone.
On Android, setting this property appends the value of the hint to the end of the accessibility label. The upside to this implementation is that it mimics the behavior of hints on iOS, but the downside to this implementation is that these hints cannot be turned off in the settings on Android the way they can be on iOS.
The reason we made this decision on Android is because normally, accessibility hints correspond with a specific action (e.g. click), and we wanted to keep behaviors consistent across platforms.
accessibilityIgnoresInvertColors
We exposed Apple's api AccessibilityIgnoresInvertColors to JavaScript, so now when you have a view where you don't want colors to be inverted (e.g image), you can set this property to true, and it won't be inverted.
These new properties will become available in the React Native 0.57 release.
If you are currently using accessibilityComponentType and accessibilityTraits, here are the steps you can take to upgrade to the new properties.
The most simple use cases can be replaced by running a jscodeshift script.
This script replaces the following instances:
accessibilityTraits=“trait”
accessibilityTraits={[“trait”]}
With
accessibilityRole= “trait”
This script also removes instances of AccessibilityComponentType (assuming everywhere you set AccessibilityComponentType, you would also set AccessibilityTraits).
For the cases that used AccessibilityTraits that don't have a corresponding value for AccessibilityRole, and the cases where multiple traits were passed into AccessibilityTraits, a manual codemod would have to be done.
In general,
accessibilityTraits= {[“button”, “selected”]}
would be manually replaced with
accessibilityRole=“button”
accessibilityStates={[“selected”]}
These properties are already being used in Facebook's codebase. The codemod for Facebook was surprisingly simple. The jscodeshift script fixed about half of our instances, and the other half was fixed manually. Overall, the entire process took less than a few hours.
Hopefully you will find the updated API useful! And please continue making apps accessible! #inclusion