Luna Wei
683b825b32
Summary: Changelog: [Internal] - Update Switch to allow injected implementations ## General understanding of the component The main flow of Switch is pretty straightforward, basically passing the props to the respective native component which uses the platform switch views on Android / iOS The interesting parts of Switch is the fact that it's a controlled component -- meaning that this component sees the JS value prop as the source of truth about the state of this component and any time the native value of the switch is out of sync with the JS value prop, we send a command `setNativeValue` to keep those in sync. The problems I ran into: * Keeping native and JS in sync * Switch skips animation occassionally on iOS simulator ## How we keep native and JS in sync By construction, the native value of the component should be the same as JS value. Then, we know the native value has changed whenever the callback `handleChange` has been fired. **Before** In the handleChange callback, we'd set an [instance variable `lastNativeValue` with the updated value](https://fburl.com/diffusion/nangxzoh) and force update. Then, in `componentDidUpdate`, we'd send the native commands if we determine that `lastNativeValue` and the `value` prop were out of sync. **After** For our modern implementation, we store the value of the switch as reported by `handleChange` and check it against the `props.value` of the switch. If they are out of sync then we will update the native switch via the switch command. **Why is `native` an object?** We need to run the `useLayoutEffect` every time `handleChange` is called independent of the value of the switch. **Why not move the logic of dispatching commands to `handleChange`?**? This would change behavior from old implementation where we would call `onChange` handlers and then re-render. Additionally, the logic to run the native commands were on `componentDidUpdate` which would've run when any prop changed. We can simplify this down to caring only when `props.value` updates. ## Unsolved, existing issue: Switches skip animation occasionally * This occurs both in the modern and old versions of Switch and I've only seen this on iOS simulators. It occurs most frequently in the "events" example where two switches' values are synced and most often the first transition after we navigate to the example surface. I have not been able to reproduce this behavior on device. * Something must be triggering a re-render in the middle of native's animation.. {F564595576} Reviewed By: nadiia, kacieb Differential Revision: D27381306 fbshipit-source-id: 06d13c6fe1ff181443f4b8dd27fb1ac65e071962
React Native
Learn once, write anywhere:
Build mobile apps with React.
Getting Started · Learn the Basics · Showcase · Contribute · Community · Support
React Native brings React's declarative UI framework to iOS and Android. With React Native, you use native UI controls and have full access to the native platform.
- Declarative. React makes it painless to create interactive UIs. Declarative views make your code more predictable and easier to debug.
- Component-Based. Build encapsulated components that manage their state, then compose them to make complex UIs.
- Developer Velocity. See local changes in seconds. Changes to JavaScript code can be live reloaded without rebuilding the native app.
- Portability. Reuse code across iOS, Android, and other platforms.
React Native is developed and supported by many companies and individual core contributors. Find out more in our ecosystem overview.
Contents
- Requirements
- Building your first React Native app
- Documentation
- Upgrading
- How to Contribute
- Code of Conduct
- License
📋 Requirements
React Native apps may target iOS 11.0 and Android 5.0 (API 21) or newer. You may use Windows, macOS, or Linux as your development operating system, though building and running iOS apps is limited to macOS. Tools like Expo can be used to work around this.
🎉 Building your first React Native app
Follow the Getting Started guide. The recommended way to install React Native depends on your project. Here you can find short guides for the most common scenarios:
📖 Documentation
The full documentation for React Native can be found on our website.
The React Native documentation discusses components, APIs, and topics that are specific to React Native. For further documentation on the React API that is shared between React Native and React DOM, refer to the React documentation.
The source for the React Native documentation and website is hosted on a separate repo, @facebook/react-native-website.
🚀 Upgrading
Upgrading to new versions of React Native may give you access to more APIs, views, developer tools, and other goodies. See the Upgrading Guide for instructions.
React Native releases are discussed in the React Native Community, @react-native-community/react-native-releases.
👏 How to Contribute
The main purpose of this repository is to continue evolving React Native core. We want to make contributing to this project as easy and transparent as possible, and we are grateful to the community for contributing bug fixes and improvements. Read below to learn how you can take part in improving React Native.
Code of Conduct
Facebook has adopted a Code of Conduct that we expect project participants to adhere to. Please read the full text so that you can understand what actions will and will not be tolerated.
Contributing Guide
Read our Contributing Guide to learn about our development process, how to propose bugfixes and improvements, and how to build and test your changes to React Native.
Open Source Roadmap
You can learn more about our vision for React Native in the Roadmap.
Good First Issues
We have a list of good first issues that contain bugs which have a relatively limited scope. This is a great place to get started, gain experience, and get familiar with our contribution process.
Discussions
Larger discussions and proposals are discussed in @react-native-community/discussions-and-proposals.
📄 License
React Native is MIT licensed, as found in the LICENSE file.
React Native documentation is Creative Commons licensed, as found in the LICENSE-docs file.