使用Expo时，您不应该自己注册应用程序，而应该让Expo自己进行注册，请记住，您必须始终导出默认组件：此外，您还需要从react-
native导入View和Button：请在下面找到完整内容码：
import React from 'react';import { AppRegistry, Text, View, Button} from 'react-native';import { StackNavigator } from 'react-navigation'; class HomeScreen extends React.Component { static navigationOptions = { title: 'Welcome', }; render() { const { navigate } = this.props.navigation; return ( <View> <Text>Hello, Chat App!</Text> <Button onPress={() => navigate('Chat', { user: 'Lucy' })} title="Chat with Lucy" /> </View> ); }} class ChatScreen extends React.Component { // Nav options can be defined as a function of the screen's props: static navigationOptions = ({ navigation }) => ({ title: `Chat with ${navigation.state.params.user}`, }); render() { // The screen's current route is passed in to `props.navigation.state`: const { params } = this.props.navigation.state; return ( <View> <Text>Chat with {params.user}</Text> </View> ); }}const SimpleAppNavigator = StackNavigator({ Home: { screen: HomeScreen }, Chat: { screen: ChatScreen }});const AppNavigation = () => ( <SimpleAppNavigator />);export default class App extends React.Component { render() { return ( <AppNavigation/> ); }}
