元素类型无效，您可能忘记导出组件

Question

尝试在 iOS 模拟器上运行我的代码时出现以下错误。错误指出 "Element type is invalid: expected a string (for built-in components) but got: undefined. You likely forgot to export your component from the file it's defined in."

我在其他人的帖子中看到了同样的问题，他们需要将 "export default App" 添加到文件末尾或在 class 的声明中使用 "export default class" .

我正在学习的教程是 https://medium.com/@gurusundesh/getting-started-with-react-native-mapview-5e0bd73aa602。可能是文章太旧了，react-native从那以后就变了。

如有任何关于如何解决此问题的建议，我们将不胜感激。

谢谢

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View
} from 'react-native';
import { MapView } from 'react-native-maps';

const instructions = Platform.select({
  ios: 'Press Cmd+R to reload,\n' +
    'Cmd+D or shake for dev menu',
  android: 'Double tap R on your keyboard to reload,\n' +
    'Shake or press menu button for dev menu',
});

class App extends Component {
  render() {
    return (
      <View style={styles.container}>
        <MapView style={styles.map}
          initialRegion={{
            latitude:10,
            longitude:20,
            latitudeDelta:30,
            longitudeDelta:40
          }}
        />
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
  map: {
    position: 'absolute',
    top: 0,
    bottom: 0,
    left: 0,
    right: 0,
  }
});

export default App;

Answer 1

将您的 MapView 导入更改为：

import MapView from 'react-native-maps';

根据文档：https://github.com/airbnb/react-native-maps

元素类型无效，您可能忘记导出组件

Element type is invalid, you likely forgot to export your component

javascript

react-native

react-native-ios