Mobile-React Native

Using Native Driver for Animated · React Native

Using Native Driver for Animated

February 14, 2017 · 7 min read

For the past year, we've been working on improving performance of animations that use the Animated library. Animations are very important to create a beautiful user experience but can also be hard to do right. We want to make it easy for developers to create performant animations without having to worry about some of their code causing it to lag.

What is this?

The Animated API was designed with a very important constraint in mind, it is serializable. This means we can send everything about the animation to native before it has even started and allows native code to perform the animation on the UI thread without having to go through the bridge on every frame. It is very useful because once the animation has started, the JS thread can be blocked and the animation will still run smoothly. In practice this can happen a lot because user code runs on the JS thread and React renders can also lock JS for a long time.

A bit of history...

This project started about a year ago, when Expo built the li.st app on Android. Krzysztof Magiera was contracted to build the initial implementation on Android. It ended up working well and li.st was the first app to ship with native driven animations using Animated. A few months later, Brandon Withrow built the initial implementation on iOS. After that, Ryan Gomba and myself worked on adding missing features like support for Animated.event as well as squash bugs we found when using it in production apps. This was truly a community effort and I would like to thanks everyone that was involved as well as Expo for sponsoring a large part of the development. It is now used by Touchable components in React Native as well as for navigation animations in the newly released React Navigation library.

How does it work?

First, let's check out how animations currently work using Animated with the JS driver. When using Animated, you declare a graph of nodes that represent the animations that you want to perform, and then use a driver to update an Animated value using a predefined curve. You may also update an Animated value by connecting it to an event of a View using Animated.event .

Here's a breakdown of the steps for an animation and where it happens:

JS: The animation driver uses requestAnimationFrame to execute on every frame and update the value it drives using the new value it calculates based on the animation curve.
JS: Intermediate values are calculated and passed to a props node that is attached to a View .
JS: The View is updated using setNativeProps .
JS to Native bridge.
Native: The UIView or android.View is updated.

As you can see, most of the work happens on the JS thread. If it is blocked the animation will skip frames. It also needs to go through the JS to Native bridge on every frame to update native views.

What the native driver does is move all of these steps to native. Since Animated produces a graph of animated nodes, it can be serialized and sent to native only once when the animation starts, eliminating the need to callback into the JS thread; the native code can take care of updating the views directly on the UI thread on every frame.

Here's an example of how we can serialize an animated value and an interpolation node (not the exact implementation, just an example).

Create the native value node, this is the value that will be animated:

NativeAnimatedModule.createNode({
  id: 1,
  type: 'value',
  initialValue: 0,
});

    
   

Create the native interpolation node, this tells the native driver how to interpolate a value:

NativeAnimatedModule.createNode({
  id: 2,
  type: 'interpolation',
  inputRange: [0, 10],
  outputRange: [10, 0],
  extrapolate: 'clamp',
});

    
   

Create the native props node, this tells the native driver which prop on the view it is attached to:

NativeAnimatedModule.createNode({
  id: 3,
  type: 'props',
  properties: ['style.opacity'],
});

    
   

Connect nodes together:

NativeAnimatedModule.connectNodes(1, 2);
NativeAnimatedModule.connectNodes(2, 3);

Connect the props node to a view:

NativeAnimatedModule.connectToView(3, ReactNative.findNodeHandle(viewRef));

With that, the native animated module has all the info it needs to update the native views directly without having to go to JS to calculate any value.

All there is left to do is actually start the animation by specifying what type of animation curve we want and what animated value to update. Timing animations can also be simplified by calculating every frame of the animation in advance in JS to make the native implementation smaller.

NativeAnimatedModule.startAnimation({
  type: 'timing',
  frames: [0, 0.1, 0.2, 0.4, 0.65, ...],
  animatedValueId: 1,
});

    
   

And now here's the breakdown of what happens when the animation runs:

Native: The native animation driver uses CADisplayLink or android.view.Choreographer to execute on every frame and update the value it drives using the new value it calculates based on the animation curve.
Native: Intermediate values are calculated and passed to a props node that is attached to a native view.
Native: The UIView or android.View is updated.

As you can see, no more JS thread and no more bridge which means faster animations! 🎉🎉

How do I use this in my app?

For normal animations the answer is simple, just add useNativeDriver: true to the animation config when starting it.

Before:

Animated.timing(this.state.animatedValue, {
  toValue: 1,
  duration: 500,
}).start();

After:

Animated.timing(this.state.animatedValue, {
  toValue: 1,
  duration: 500,
  useNativeDriver: true, // <-- Add this
}).start();

    
   

Animated values are only compatible with one driver so if you use native driver when starting an animation on a value, make sure every animation on that value also uses the native driver.

It also works with Animated.event , this is very useful if you have an animation that must follow the scroll position because without the native driver it will always run a frame behind of the gesture because of the async nature of React Native.

Before:

<ScrollView
  scrollEventThrottle={16}
  onScroll={Animated.event(
    [{ nativeEvent: { contentOffset: { y: this.state.animatedValue } } }]
  )}
>
  {content}
</ScrollView>

    
   

After:

<Animated.ScrollView // <-- Use the Animated ScrollView wrapper
  scrollEventThrottle={1} // <-- Use 1 here to make sure no events are ever missed
  onScroll={Animated.event(
    [{ nativeEvent: { contentOffset: { y: this.state.animatedValue } } }],
    { useNativeDriver: true } // <-- Add this
  )}
>
  {content}
</Animated.ScrollView>

    
   

Caveats

Not everything you can do with Animated is currently supported in Native Animated. The main limitation is that you can only animate non-layout properties, things like transform and opacity will work but Flexbox and position properties won't. Another one is with Animated.event , it will only work with direct events and not bubbling events. This means it does not work with PanResponder but does work with things like ScrollView#onScroll .

Native Animated has also been part of React Native for quite a while but has never been documented because it was considered experimental. Because of that make sure you are using a recent version (0.40+) of React Native if you want to use this feature.

Resources

For more information about animated I recommend watching this talk by Christopher Chedeau.

If you want a deep dive into animations and how offloading them to native can improve user experience there is also this talk by Krzysztof Magiera.

Better List Views in React Native · React Native

Better List Views in React Native

March 13, 2017 · 6 min read

Spencer Ahrens

Software Engineer at Facebook

Many of you have started playing with some of our new List components already after our teaser announcement in the community group, but we are officially announcing them today! No more ListView s or DataSource s, stale rows, ignored bugs, or excessive memory consumption - with the latest React Native March 2017 release candidate ( 0.43-rc.1 ) you can pick from the new suite of components what best fits your use-case, with great perf and feature sets out of the box:

`<FlatList>`

This is the workhorse component for simple, performant lists. Provide an array of data and a renderItem function and you're good to go:

<FlatList
  data={[{title: 'Title Text', key: 'item1'}, ...]}
  renderItem={({item}) => <ListItem title={item.title} />}
/>

`<SectionList>`

If you want to render a set of data broken into logical sections, maybe with section headers (e.g. in an alphabetical address book), and potentially with heterogeneous data and rendering (such as a profile view with some buttons followed by a composer, then a photo grid, then a friend grid, and finally a list of stories), this is the way to go.

<SectionList
  renderItem={({item}) => <ListItem title={item.title} />}
  renderSectionHeader={({section}) => <H1 title={section.key} />}
  sections={[ // homogeneous rendering between sections
    {data: [...], key: ...},
    {data: [...], key: ...},
    {data: [...], key: ...},
  ]}
/>

<SectionList
  sections={[ // heterogeneous rendering between sections
    {data: [...], key: ..., renderItem: ...},
    {data: [...], key: ..., renderItem: ...},
    {data: [...], key: ..., renderItem: ...},
  ]}
/>

    
   

`<VirtualizedList>`

The implementation behind the scenes with a more flexible API. Especially handy if your data is not in a plain array (e.g. an immutable list).

Features

Lists are used in many contexts, so we packed the new components full of features to handle the majority of use cases out of the box:

Scroll loading ( onEndReached ).
Pull to refresh ( onRefresh / refreshing ).
Configurable viewability (VPV) callbacks ( onViewableItemsChanged / viewabilityConfig ).
Horizontal mode ( horizontal ).
Intelligent item and section separators.
Multi-column support ( numColumns )
scrollToEnd , scrollToIndex , and scrollToItem
Better Flow typing.

Some Caveats

The internal state of item subtrees is not preserved when content scrolls out of the render window. Make sure all your data is captured in the item data or external stores like Flux, Redux, or Relay.

These components are based on PureComponent which means that they will not re-render if props remains shallow-equal. Make sure that everything your renderItem function depends on directly is passed as a prop that is not === after updates, otherwise your UI may not update on changes. This includes the data prop and parent component state. For example:

<FlatList
  data={this.state.data}
  renderItem={({item}) => (
    <MyItem
      item={item}
      onPress={() =>
        this.setState(oldState => ({
          selected: {
            // New instance breaks `===`
            ...oldState.selected, // copy old data
            [item.key]: !oldState.selected[item.key], // toggle
          },
        }))
      }
      selected={
        !!this.state.selected[item.key] // renderItem depends on state
      }
    />
  )}
  selected={
    // Can be any prop that doesn't collide with existing props
    this.state.selected // A change to selected should re-render FlatList
  }
/>

      
     

In order to constrain memory and enable smooth scrolling, content is rendered asynchronously offscreen. This means it's possible to scroll faster than the fill rate and momentarily see blank content. This is a tradeoff that can be adjusted to suit the needs of each application, and we are working on improving it behind the scenes.
By default, these new lists look for a key prop on each item and use that for the React key. Alternatively, you can provide a custom keyExtractor prop.

Performance

Besides simplifying the API, the new list components also have significant performance enhancements, the main one being nearly constant memory usage for any number of rows. This is done by 'virtualizing' elements that are outside of the render window by completely unmounting them from the component hierarchy and reclaiming the JS memory from the react components, along with the native memory from the shadow tree and the UI views. This has a catch which is that internal component state will not be preserved, so make sure you track any important state outside of the components themselves, e.g. in Relay or Redux or Flux store.

Limiting the render window also reduces the amount of work that needs to be done by React and the native platform, e.g from view traversals. Even if you are rendering the last of a million elements, with these new lists there is no need to iterate through all those elements in order to render. You can even jump to the middle with scrollToIndex without excessive rendering.

We've also made some improvements with scheduling which should help with application responsiveness. Items at the edge of the render window are rendered infrequently and at a lower priority after any active gestures or animations or other interactions have completed.

Advanced Usage

Unlike ListView , all items in the render window are re-rendered any time any props change. Often this is fine because the windowing reduces the number of items to a constant number, but if your items are on the complex side, you should make sure to follow React best practices for performance and use React.PureComponent and/or shouldComponentUpdate as appropriate within your components to limit re-renders of the recursive subtree.

If you can calculate the height of your rows without rendering them, you can improve the user experience by providing the getItemLayout prop. This makes it much smoother to scroll to specific items with e.g. scrollToIndex , and will improve the scroll indicator UI because the height of the content can be determined without rendering it.

If you have an alternative data type, like an immutable list, <VirtualizedList> is the way to go. It takes a getItem prop that lets you return the item data for any given index and has looser flow typing.

There are also a bunch of parameters you can tweak if you have an unusual use case. For example, you can use windowSize to trade off memory usage vs. user experience, maxToRenderPerBatch to adjust fill rate vs. responsiveness, onEndReachedThreshold to control when scroll loading happens, and more.

Future Work

Migration of existing surfaces (ultimately deprecation of ListView ).
More features as we see/hear the need (let us know!).
Sticky section header support.
More performance optimizations.
Support functional item components with state.

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idx: The Existential Function · React Native

idx: The Existential Function

March 13, 2017 · 2 min read

Timothy Yung

Engineering Manager at Facebook

At Facebook, we often need to access deeply nested values in data structures fetched with GraphQL. On the way to accessing these deeply nested values, it is common for one or more intermediate fields to be nullable. These intermediate fields may be null for a variety of reasons, from failed privacy checks to the mere fact that null happens to be the most flexible way to represent non-fatal errors.

Unfortunately, accessing these deeply nested values is currently tedious and verbose.

props.user &&
  props.user.friends &&
  props.user.friends[0] &&
  props.user.friends[0].friends;

There is an ECMAScript proposal to introduce the existential operator which will make this much more convenient. But until a time when that proposal is finalized, we want a solution that improves our quality of life, maintains existing language semantics, and encourages type safety with Flow.

We came up with an existential function we call idx .

idx(props, _ => _.user.friends[0].friends);

The invocation in this code snippet behaves similarly to the boolean expression in the code snippet above, except with significantly less repetition. The idx function takes exactly two arguments:

Any value, typically an object or array into which you want to access a nested value.
A function that receives the first argument and accesses a nested value on it.

In theory, the idx function will try-catch errors that are the result of accessing properties on null or undefined. If such an error is caught, it will return either null or undefined. (And you can see how this might be implemented in idx.js.)

In practice, try-catching every nested property access is slow, and differentiating between specific kinds of TypeErrors is fragile. To deal with these shortcomings, we created a Babel plugin that transforms the above idx invocation into the following expression:

props.user == null
  ? props.user
  : props.user.friends == null
  ? props.user.friends
  : props.user.friends[0] == null
  ? props.user.friends[0]
  : props.user.friends[0].friends;

    
   

Finally, we added a custom Flow type declaration for idx that allows the traversal in the second argument to be properly type-checked while permitting nested access on nullable properties.

The function, Babel plugin, and Flow declaration are now available on GitHub. They are used by installing the idx and babel-plugin-idx npm packages, and adding “idx” to the list of plugins in your .babelrc file.

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Introducing Create React Native App · React Native

Introducing Create React Native App

March 13, 2017 · 2 min read

Adam Perry

Software Engineer at Expo

Today we’re announcing Create React Native App: a new tool that makes it significantly easier to get started with a React Native project! It’s heavily inspired by the design of Create React App and is the product of a collaboration between Facebook and Expo (formerly Exponent).

Many developers struggle with installing and configuring React Native’s current native build dependencies, especially for Android. With Create React Native App, there’s no need to use Xcode or Android Studio, and you can develop for your iOS device using Linux or Windows. This is accomplished using the Expo app, which loads and runs CRNA projects written in pure JavaScript without compiling any native code.

Try creating a new project (replace with suitable yarn commands if you have it installed):

$ npm i -g create-react-native-app
$ create-react-native-app my-project
$ cd my-project
$ npm start

This will start the React Native packager and print a QR code. Open it in the Expo app to load your JavaScript. Calls to console.log are forwarded to your terminal. You can make use of any standard React Native APIs as well as the Expo SDK.

What about native code?

Many React Native projects have Java or Objective-C/Swift dependencies that need to be compiled. The Expo app does include APIs for camera, video, contacts, and more, and bundles popular libraries like Airbnb’s react-native-maps, or Facebook authentication. However if you need a native code dependency that Expo doesn’t bundle then you’ll probably need to have your own build configuration for it. Just like Create React App, “ejecting” is supported by CRNA.

You can run npm run eject to get a project very similar to what react-native init would generate. At that point you’ll need Xcode and/or Android Studio just as you would if you started with react-native init , adding libraries with react-native link will work, and you’ll have full control over the native code compilation process.

Questions? Feedback?

Create React Native App is now stable enough for general use, which means we’re very eager to hear about your experience using it! You can find me on Twitter or open an issue on the GitHub repository. Pull requests are very welcome!

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React Native Monthly #1 · React Native

React Native Monthly #1

June 21, 2017 · 6 min read

Tomislav Tenodi

Product Manager at Shoutem

At Shoutem, we've been fortunate enough to work with React Native from its very beginnings. We decided we wanted to be part of the amazing community from day one. Soon enough, we realized it's almost impossible to keep up with the pace the community was growing and improving. That's why we decided to organize a monthly meeting where all major React Native contributors can briefly present what their efforts and plans are.

Monthly meetings

We had our first session of the monthly meeting on June 14, 2017. The mission for React Native Monthly is simple and straightforward: improve the React Native community . Presenting teams' efforts eases collaboration between teams done offline.

Teams

On the first meeting, we had 8 teams join us:

Airbnb
Callstack
Expo
Facebook
GeekyAnts
Microsoft
Shoutem
Wix

We hope to have more core contributors join the upcoming sessions!

Notes

As teams' plans might be of interest to a broader audience, we'll be sharing them here, on the React Native blog. So, here they are:

Airbnb

Plans to add some A11y (accessibility) APIs to View and the AccessibilityInfo native module.
Will be investigating adding some APIs to native modules on Android to allow for specifying threads for them to run on.
Have been investigating potential initialization performance improvements.
Have been investigating some more sophisticated bundling strategies to use on top of "unbundle".

Callstack

Looking into improving the release process by using Detox for E2E testing. Pull request should land soon.
Blob pull request they have been working on has been merged, subsequent pull requests coming up.
Increasing Haul adoption across internal projects to see how it performs compared to Metro Bundler. Working on better multi-threaded performance with the Webpack team.
Internally, they have implemented a better infrastructure to manage open source projects. Plans to be getting more stuff out in upcoming weeks.
The React Native Europe conference is coming along, nothing interesting yet, but y'all invited!
Stepped back from react-navigation for a while to investigate alternatives (especially native navigations).

Expo

Working on making it possible to install npm modules in Snack, will be useful for libraries to add examples to documentation.
Working with Krzysztof and other people at Software Mansion on a JSC update on Android and a gesture handling library.
Adam Miskiewicz is transitioning his focus towards react-navigation.
Create React Native App is in the Getting Started guide in the docs. Expo wants to encourage library authors to explain clearly whether their lib works with CRNA or not, and if so, explain how to set it up.

Facebook

React Native's packager is now Metro Bundler, in an independent repo. The Metro Bundler team in London is excited to address the needs of the community, improve modularity for additional use-cases beyond React Native, and increase responsiveness on issues and PRs.
In the coming months, the React Native team will work on refining the APIs of primitive components. Expect improvements in layout quirks, accessibility, and flow typing.
The React Native team also plans on improving core modularity this year, by refactoring to fully support 3rd party platforms such as Windows and macOS.

GeekyAnts

The team is working on a UI/UX design app (codename: Builder) which directly works with .js files. Right now, it supports only React Native. It’s similar to Adobe XD and Sketch.
The team is working hard so that you can load up an existing React Native app in the editor, make changes (visually, as a designer) and save the changes directly to the JS file.
Folks are trying to bridge the gap between Designers and Developers and bring them on the same repo.
Also, NativeBase recently reached 5,000 GitHub stars.

Microsoft

CodePush has now been integrated into Mobile Center. This is the first step in providing a much more integrated experience with distribution, analytics and other services. See their announcement here.
VS Code has a bug with debugging, they are working on fixing that right now and will have a new build.
Investigating Detox for Integration testing, looking at JSC Context to get variables alongside crash reports.

Shoutem

Making it easier to work on Shoutem apps with tools from the React Native community. You will be able to use all the React Native commands to run the apps created on Shoutem.
Investigating profiling tools for React Native. They had a lot of problems setting it up and they will write some of the insights they discovered along the way.
Shoutem is working on making it easier to integrate React Native with existing native apps. They will document the concept that they developed internally in the company, in order to get the feedback from the community.

Wix

Working internally to adopt Detox to move significant parts of the Wix app to "zero manual QA". As a result, Detox is being used heavily in a production setting by dozens of developers and maturing rapidly.
Working to add support to the Metro Bundler for overriding any file extension during the build. Instead of just "ios" and "android", it would support any custom extension like "e2e" or "detox". Plans to use this for E2E mocking. There's already a library out called react-native-repackager, now working on a PR.
Investigating automation of performance tests. This is a new repo called DetoxInstruments. You can take a look, it's being developed open source.
Working with a contributor from KPN on Detox for Android and supporting real devices.
Thinking about "Detox as a platform" to allow building other tools that need to automate the simulator/device. An example is Storybook for React Native or Ram's idea for integration testing.

Next session

Meetings will be held every four weeks. The next session is scheduled for July 12, 2017. As we just started with this meeting, we'd like to know how do these notes benefit the React Native community. Feel free to ping me on Twitter if you have any suggestion on what we should cover in the following sessions, or how we should improve the output of the meeting.

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React Native Monthly #2 · React Native

React Native Monthly #2

July 28, 2017 · 8 min read

Tomislav Tenodi

Product Manager at Shoutem

The React Native monthly meeting continues! On this session, we were joined by Infinite Red, great minds behind Chain React, the React Native Conference. As most of the people here were presenting talks at Chain React, we pushed the meeting to a week later. Talks from the conference have been posted online and I encourage you to check them out. So, let's see what our teams are up to.

Teams

On this second meeting, we had 9 teams join us:

Airbnb
Callstack
Expo
Facebook
GeekyAnts
Infinite Red
Microsoft
Shoutem
Wix

Notes

Here are the notes from each team:

Airbnb

Check out the Airbnb repository for React Native related projects.

Callstack

Mike Grabowski has been managing React Native's monthly releases as always, including a few betas that were pushed out. In particular, working on getting a v0.43.5 build published to npm since it unblocks Windows users!
Slow but consistent work is happening on Haul. There is a pull request that adds HMR, and other improvements have shipped. Recently got a few industry leaders to adopt it. Possibly planning to start a full-time paid work in that area.
Michał Pierzchała from the Jest team has joined us at Callstack this month. He will help maintain Haul and possibly work on Metro Bundler and Jest.
Satyajit Sahoo is now with us, yay!
Got a bunch of cool stuff coming up from our OSS department. In particular, working on bringing Material Palette API to React Native. Planning to finally release our native iOS kit which is aimed to provide 1:1 look & feel of native components.

Expo

Recently launched Native Directory to help with discoverability and evaluation of libraries in React Native ecosystem. The problem: lots of libraries, hard to test, need to manually apply heuristics and not immediately obvious which ones are just the best ones that you should use. It's also hard to know if something is compatible with CRNA/Expo. So Native Directory tries to solve these problems. Check it out and add your library to it. The list of libraries is in here. This is just our first pass of it, and we want this to be owned and run by the community, not just Expo folks. So please pitch in if you think this is valuable and want to make it better!
Added initial support for installing npm packages in Snack with Expo SDK 19. Let us know if you run into any issues with it, we are still working through some bugs. Along with Native Directory, this should make it easy to test libraries that have only JS dependencies, or dependencies included in Expo SDK. Try it out:
- react-native-modal
- react-native-animatable
- react-native-calendars
Released Expo SDK19 with a bunch of improvements across the board, and we're now using the updated Android JSC.
Working on a guide in docs with Alexander Kotliarskyi with a list of tips on how to improve the user experience of your app. Please join in and add to the list or help write some of it!
- Issue: #14979
- Initial pull request: #14993
Continuing to work on: audio/video, camera, gestures (with Software Mansion, react-native-gesture-handler ), GL camera integration and hoping to land some of these for the first time in SDK20 (August), and significant improvements to others by then as well. We're just getting started on building infrastructure into the Expo client for background work (geolocation, audio, handling notifications, etc.).
Adam Miskiewicz has made some nice progress on imitating the transitions from UINavigationController in react-navigation. Check out an earlier version of it in his tweet - release coming with it soon. Also check out MaskedViewIOS which he upstreamed. If you have the skills and desire to implement MaskedView for Android that would be awesome!

Facebook

Facebook is internally exploring being able to embed native ComponentKit and Litho components inside of React Native.
Contributions to React Native are very welcome! If you are wondering how you can contribute, the "How to Contribute" guide describes our development process and lays out the steps to send your first pull request. There are other ways to contribute that do not require writing code, such as by triaging issues or updating the docs.
- At the time of writing, React Native has 635 open issues and 249 open pull requests. This is overwhelming for our maintainers, and when things get fixed internally, it is difficult to ensure the relevant tasks are updated.
- We are unsure what the best approach is to handle this while keeping the community satisfied. Some (but not all!) options include closing stale issues, giving significantly more people permissions to manage issues, and automatically closing issues that do not follow the issue template. We wrote a "What to Expect from Maintainers" guide to set expectations and avoid surprises. If you have ideas on how we can make this experience better for maintainers as well as ensuring people opening issues and pull requests feel heard and valued, please let us know!

GeekyAnts

We demoed the Designer Tool which works with React Native files on Chain React. Many attendees signed up for the waiting list.
We are also looking at other cross-platform solutions like Google Flutter (a major comparison coming along), Kotlin Native, and Apache Weex to understand the architectural differences and what we can learn from them to improve the overall performance of React Native.
Switched to react-navigation for most of our apps, which has improved the overall performance.
Also, announced NativeBase Market - A marketplace for React Native components and apps (for and by the developers).

Infinite Red

We want to introduce the Reactotron. Check out the introductory video. We'll be adding more features very soon!
Organised Chain React Conference. It was awesome, thanks all for coming! The videos are now online!

Microsoft

CodePush has now been integrated into Mobile Center. Existing users will have no change in their workflow.
- Some people have reported an issue with duplicate apps - they already had an app on Mobile Center. We are working on resolving them, but if you have two apps, let us know, and we can merge them for you.
Mobile Center now supports Push Notifications for CodePush. We also showed how a combination of Notifications and CodePush could be used for A/B testing apps - something unique to the ReactNative architecture.
VS Code has a known debugging issue with ReactNative - the next release of the extension in a couple of days will be fixing the issue.
Since there are many other teams also working on React Native inside Microsoft, we will work on getting better representation from all the groups for the next meeting.

Shoutem

Finished the process of making the React Native development easier on Shoutem. You can use all the standard react-native commands when developing apps on Shoutem.
We did a lot of work trying to figure out how to best approach the profiling on React Native. A big chunk of documentation is outdated, and we'll do our best to create a pull request on the official docs or at least write some of our conclusions in a blog post.
Switching our navigation solution to react-navigation, so we might have some feedback soon.
We released a new HTML component in our toolkit which transforms the raw HTML to the React Native components tree.

Wix

We started working on a pull request to Metro Bundler with react-native-repackager capabilities. We updated react-native-repackager to support RN 44 (which we use in production). We are using it for our mocking infrastructure for detox.
We have been covering the Wix app in detox tests for the last three weeks. It's an amazing learning experience of how to reduce manual QA in an app of this scale (over 40 engineers). We have resolved several issues with detox as a result, a new version was just published. I am happy to report that we are living up to the "zero flakiness policy" and the tests are passing consistently so far.
Detox for Android is moving forward nicely. We are getting significant help from the community. We are expecting an initial version in about two weeks.
DetoxInstruments, our performance testing tool, is getting a little bigger than we originally intended. We are now planning to turn it into a standalone tool that will not be tightly coupled to detox. It will allow investigating the performance of iOS apps in general. It will also be integrated with detox so we can run automated tests on performance metrics.

Next session

The next session is scheduled for August 16, 2017. As this was only our second meeting, we'd like to know how do these notes benefit the React Native community. Feel free to ping me on Twitter if you have any suggestion on how we should improve the output of the meeting.

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