更新

时刻将 React Native 更新到最新的版本，可以获得更多 API、视图、开发者工具以及其他一些好东西（译注：官方开发任务繁重，人手紧缺，几乎不会对旧版本提供维护支持，所以即便更新可能带来一些兼容上的变更，但建议开发者还是尽一切可能第一时间更新）。由于一个完整的 React Native 项目是由 Android 项目、iOS 项目和 JavaScript 项目组成的，且都打包在一个 npm 包中，所以升级可能会有一些麻烦。我们会尽量简化这一流程。你可以在项目目录下使用npx react-native info命令查看当前的版本。There's currently two ways for upgrading your React Native project: by using React Native CLI or manually with Upgrade Helper.

译注：英文更新日志点这里查看。

Expo projects

Upgrading your Expo project to a new version of React Native requires updating the react-native, react, and expo package versions in your package.json file. Expo provides an upgrade command to handle upgrading these and any other known dependencies for you. See the Upgrading Expo SDK Walkthrough for up-to-date information about upgrading your project.

React Native projects

Because typical React Native projects are essentially made up of an Android project, an iOS project, and a JavaScript project, upgrading can be rather tricky. The Upgrade Helper is a web tool to help you out when upgrading your apps by providing the full set of changes happening between any two versions. It also shows comments on specific files to help understanding why that change is needed.

1. Select the versions

You first need to select from and to which version you wish to upgrade, by default the latest major versions are selected. After selecting you can click the button "Show me how to upgrade".

💡 Major updates will show an "useful content" section on the top with links to help you out when upgrading.

tip

Or you can run the npx react-native upgrade, which will automatically check your current version and the latest version available and will show you the link to the Upgrade Helper page with the versions already selected.

2. Upgrade dependencies

The first file that is shown is the package.json, it's good to update the dependencies that are showing in there. For example, if react-native and react appears as changes then you can install it in your project by running following commands:

npm

# {{VERSION}} and {{REACT_VERSION}} are the release versions showing in the diff
npm install react-native@{{VERSION}}
npm install react@{{REACT_VERSION}}

Yarn

# {{VERSION}} and {{REACT_VERSION}} are the release versions showing in the diff
yarn add react-native@{{VERSION}}
yarn add react@{{REACT_VERSION}}

3. Upgrade your project files

The new release may contain updates to other files that are generated when you run npx react-native init, those files are listed after the package.json in the Upgrade Helper page. If there aren't other changes then you only need to rebuild the project to continue developing.

In case there are changes then you can either update them manually by copying and pasting from the changes in the page or you can do it with the React Native CLI upgrade command by running:

npx react-native upgrade

This will check your files against the latest template and perform the following:

• If there is a new file in the template, it is created.
• If a file in the template is identical to your file, it is skipped.
• If a file is different in your project than the template, you will be prompted; you have options to keep your file or overwrite it with the template version.

Some upgrades won't be done automatically with the React Native CLI and require manual work, e.g. 0.28 to 0.29, or 0.56 to 0.57. Make sure to check the release notes when upgrading so that you can identify any manual changes your particular project may require.

Troubleshooting

I have done all the changes but my app is still using an old version

These sort of errors are usually related to caching, it's recommended to install react-native-clean-project to clear all your project's cache and then you can run it again.

手动升级

升级过程往往会碰到很多问题，尤其涉及到众多第三方时，处理起来尤为费时费力。此时建议可以尝试直接 init 一个新的项目，然后把现有项目的 JS 代码进行手动迁移。