RN错误集

错误集

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创建新项目时，本地已经安装好pod，每次都要提示安装pod，然后又安装失败
npx react-native init AwesomeProject
如果本地安装的pod与rn默认的不一致，会报错

Installing dependencies
✔ CocoaPods (https://cocoapods.org/) is not installed. CocoaPods is necessary for the iOS project to run correctly. Do you want to install it? › Yes, with gem (may require sudo)
✔ Installing CocoaPods
✖ Installing CocoaPods dependencies (this may take a few minutes)
✖ Installing CocoaPods dependencies (this may take a few minutes)
error Error: Failed to install CocoaPods dependencies for iOS project, which is required by this template.
Please try again manually: "cd ./Sample3/ios && pod install".
CocoaPods documentation: https://cocoapods.org/

使用跳过install即可
npx react-native init AwesomeProject --skip-install

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bundle install
Your Ruby version is 2.6.6, but your Gemfile specified 2.7.5

解决方案：将Gemfile里的版本改成设置提示版本即可

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参考：Shell/Bash - 如何全局卸载react native cli
npx react-native init AwesomeProject
报错

,,,,typeError: cli.init is not a function

删除全局的react-native-cli
npm uninstall -g react-native-cli

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参考：避免在unmounted组件上调用setState
避免在unmounted的组件上设置state

Warning: Can't perform a React state update on an unmounted component. This is a no-op, but it indicates a memory leak in your application. To fix, cancel all subscriptions and asynchronous tasks in the componentWillUnmount method.

主要场景是一些定时器延迟执行的时候，组件已经删除了还在设置state，
1、class的组件在componentWillUnmount方法里销毁掉定时器

componentWillUnmount() {
  clearTimeout(xx);
}

2、function的组件在useEffect里销毁定时器

useEffect(()=>{ 
  return () =>{ clearTimeout(xx); }
  },
[])

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在组件还没有加载好就设置内容，常见的场景是设置导航栏右侧的按钮

ExceptionsManager.js:149 Warning: Cannot update a component (NativeStackNavigator) while rendering a different component (observerComponent). To locate the bad setState() call insideobserverComponent, follow the stack trace as described in

修改方式，将设置内容放到mounted之后
class组件

componentDidMount() {
    this.props.navigation.setOptions({headerRight: (<Button title='AAAA'/>)  })
  }

function组件

useEffect(() => {
     navigation.setOptions({headerRight: (<Button title='AAAA'/>)})
}, []);