68b0d4d510
Summary: The main goal of this change is to fix an issue that happens on iOS when the native app starts before the packager server is available which causes app reloads to fail continually until the app is restarted. What happens is that with the current setup we call `RCTBundleURLProvider#jsBundleURLForBundleRoot` once in `AppDelegate#didFinishLaunchingWithOptions`. If at that point the packager server is not running yet it will return nil (expected behaviour) and that will be passed to the bridge constructor. Subsequent reloads will keep trying to load this nil bundle url since it has no way to ask `RCTBundleURLProvider` for a new url now that the packager is actually running. We can fix this by using `RCTBridgeDelegate` instead which is a lot more flexible. Instead of passing the bundle url at construction time it will call the `sourceURLForBridge` method each time the bridge is reloaded. This means that even if the packager is not running yet and that `RCTBundleURLProvider` returns nil for the first invocation, subsequent reloads will call `RCTBundleURLProvider` again for a new value. Changelog: ---------- [iOS] [Added] - Use RCTBridgeDelegate in the new project template Pull Request resolved: https://github.com/facebook/react-native/pull/23031 Differential Revision: D13710048 Pulled By: cpojer fbshipit-source-id: 0059c5c962d508737ae410a82315c11ad305efe8
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.