6a3d9c06ce
Summary: Changelog: ---------- [Android] [Fixed] - Fix Picker.onValueChange sometimes not fired due to race condition. Fixes #15556 Root Cause: ------------ Please check my code snippet at https://snack.expo.io/kudochien/android-picker-issue and try to select different items on Picker to see if console.log() hit. If calling setState() with some latency, e.g. setTimeout() or changes from redux, the second time changing picker item on UI, the onValueChange() will be not fired. The root cause comes from the `forceUpdate` in PickerAndroid.android.js. If user's setState() update comes after forceUpdate(), the flow will be: 1. First time select picker item 2. onValueChange + forceUpdate 3. user's setState() + componentDidUpdate + setNativeProps({ selected: ... }) 4. mSuppressNextEvent = true 5. Second time select picker item 6. Since mSuppressNextEvent is true, the onValueChange will not be fired. Solution: --------- Like other controlled components, disable change listener during setup values from JS. Android Spinner `setSelection(int position)` is asynchronous call, i.e. will fire onItemSelected in next run loop and is not suitable for us. `setSelection(int position, boolean animate)`, however, is synchronous call which I used. Some more references about setSelection: https://stackoverflow.com/a/43512925/2590265 http://androidxref.com/8.1.0_r33/xref/frameworks/base/core/java/android/widget/AbsSpinner.java#276 The two arguments version will use `setSelectionInt()` which set mBlockLayoutRequests as true to prevent onItemSelected call from next layout(). I also moved the setOnItemSelectedListener() call after onLayout to prevent onValueChange() during intialization. Pull Request resolved: https://github.com/facebook/react-native/pull/22821 Differential Revision: D13731979 Pulled By: cpojer fbshipit-source-id: e06bd9aa62463b66c8f3fd7214485898d5375054
React Native · 
Learn once, write anywhere: Build mobile apps with React.
See the official React Native website for an introduction to React Native.
Requirements
Supported target operating systems are >= Android 4.1 (API 16) and >= iOS 9.0. You may use Windows, macOS, or Linux as your development operating system, though building and running iOS apps is limited to macOS by default (tools like Expo can be used to get 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:
How React Native works
React Native lets you build mobile apps using JavaScript. It uses the same design as React, letting you compose a rich mobile UI from declarative components.
With React Native, you don't build a "mobile web app", an "HTML5 app", or a "hybrid app". You build a real mobile app that's indistinguishable from an app built using Objective-C, Java, Kotlin, or Swift. React Native uses the same fundamental UI building blocks as regular iOS and Android apps. You just put those building blocks together using JavaScript and React.
React Native lets you build your app faster. Instead of recompiling, you can reload your app instantly. With hot reloading, you can even run new code while retaining your application state.
React Native combines smoothly with components written in Objective-C, Java, Kotlin, or Swift. It's simple to drop down to native code if you need to optimize a few aspects of your application. It's also easy to build part of your app in React Native, and part of your app using native code directly - that's how the Facebook app works.
The focus of React Native is on developer efficiency across all the platforms you care about - learn once, write anywhere. Facebook uses React Native in multiple production apps and will continue investing in React Native. You can learn more about our open source roadmap in this blog post: Open Source Roadmap.
Full documentation
The full documentation for React Native can be found on our website. The source for the React Native documentation and website is hosted on a separate repo, https://github.com/facebook/react-native-website. Releases are discussed in the React Native Community, https://github.com/react-native-community/react-native-releases, and larger discussions and proposals are in https://github.com/react-native-community/discussions-and-proposals.
The React Native documentation only discusses the components, APIs, and topics specific to React Native (React on iOS and Android). For further documentation on the React API that is shared between React Native and React DOM, refer to the React documentation.
Join the React Native community
- Website: https://facebook.github.io/react-native
- Twitter: https://twitter.com/reactnative
- Help: https://facebook.github.io/react-native/en/help
See the CONTRIBUTING file for how to help out.
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.