static navigationOptions = {
 title: ({ state }) => `Chat with ${state.params.user}`
 };

/** 
* Sample React Native App 
* https://github.com/facebook/react-native 
* @flow
 */
import {
 AppRegistry,
}from 'react-native';
import rootApp from './js/rootApp'
AppRegistry.registerComponent('GankProject', () = >rootApp);

/**
 * Created by Administrator on 2017/3/31 0031. 
*/
'use strict'import React from 'react';
import {
 AppRegistry,
 Text,
 View,
 Button,
}
from 'react-native';
import {
 StackNavigator
}
from 'react-navigation';
import ChatScreen from './ChatScreen';
class HomeScreen extends React.Component {
 static navigationOptions = {
 title: 'Welcome',
 //設置標題內容 }; 
 render() {
 const {
 navigate
 } = this.props.navigation;
 return ( < View > <Text > Hello, Navigation ! </Text> 
 <Button 
 onPress={() => navigate('Chat',{user:'Lucy'})} 
 title="Chat with Lucy"/ > </View> 
 ); 
 }
} 
const SimpleApp = StackNavigator(
{ 
 Home: {screen: HomeScreen}, 
 Chat:{screen:ChatScreen}, 
}
); 
export default SimpleApp;

/**
 * Created by Administrator on 2017/3/31 0031. 
*/
'use strict'
import React,{Component}from 'react';
import {View,Text}from 'react-native';
class ChatScreen extends Component {
 static navigationOptions = {
 title: ({state}) = >`Chat with $ {state.params.user}`
 };
 render() {
 const {params} = this.props.navigation.state;
 return ( < View > <Text > Chat with {
 params.user
 } < /Text> </View > );
 }
}
export default ChatScreen;

/** * Created by Administrator on 2017/3/31 0031. */
'use strict'
import React, { Component}from 'react';
import {View, Text, Button}from 'react-native';
class ChatScreen extends Component {
 static navigationOptions = {
 title: ({
 state
 }) => {
 if (state.params.mode === 'info') {
 return `${state.params.user}'s Contact Info`;
 }
 return `Chat with ${state.params.user}`;
 },
 header: ({state, setParams}) => {
 // The navigation prop has functions like setParams, goBack, and navigate. 
 let right = ( < Button title = {
 `${state.params.user}'s info`
 }
 onPress = {
 () => setParams({
 mode: 'info'
 })
 }
 /> 
 ); 
 if (state.params.mode === 'info') { 
 right = ( 
 <Button 
 title="Done" 
 onPress={() => setParams({ mode: 'none' })} 
 / >
 );
 }
 return {right};
 },
};
render() {
 const {
 params
 } = this.props.navigation.state;
 return ( 
 < View >
 < Text > Chat with {params.user} < /Text> 
 </View >
 );
}
}
export default ChatScreen;