block6.js

// ScreenThree.js
import React, { Component } from 'react';
import { StyleSheet, View, Text, TouchableHighlight } from 'react-native';

class ScreenThree extends Component {
	static navigationOptions = ({ navigation }) => ({
		title: `Welcome ${navigation.state.params.screen}`
	});

	render() {
		const { params } = this.props.navigation.state;
		return (
			<View style={styles.container}>
				<Text style={styles.titleText}>{params.screen}</Text>
				<TouchableHighlight
					style={styles.button}
					onPress={() => this.props.navigation.goBack()}
				>
					<Text style={styles.buttonText}>Go Back</Text>
				</TouchableHighlight>
			</View>
		);
	}
}

const styles = StyleSheet.create({
	container: {
		flex: 1,
		justifyContent: 'center',
		alignItems: 'center'
	},
	titleText: {
		fontSize: 22
	},
	button: {
		alignSelf: 'stretch',
		marginRight: 25,
		marginLeft: 25,
		marginTop: 20,
		borderRadius: 20,
		backgroundColor: '#ff0044',
		height: 50,
		justifyContent: 'center'
	},
	buttonText: {
		color: 'white',
		fontSize: 18,
		alignSelf: 'center'
	}
});

export default ScreenThree;