import React from "react";
import { View, Text } from "react-native";
import { createStackNavigator } from "react-navigation";
class HomeScreen extends React.Component {
render() {
return (
<View style={{ flex: 1, alignItems: "center", justifyContent: "center" }}>
<Text>Home Screen-</Text>
</View>
);
}
}
class DetailsScreen extends React.Component {
render() {
return (
<View style={{ flex: 1, alignItems: "center", justifyContent: "center" }}>
<Text>Details Screen</Text>
</View>
);
}
}
const RootStack = createStackNavigator(
{
Home: HomeScreen,
Details: DetailsScreen,
},
{
initialRouteName: "Home",
}
); 
everybody help me ~