message: Animated discription text in and out
diff: import React from 'react';
  -import {StyleSheet, View, ScrollView, Image, Text, TouchableOpacity, Dimensions, Platform} from 'react-native';
  +import {StyleSheet, View, ScrollView, Image, Text, TouchableOpacity, Animated, Dimensions, Platform} from 'react-native';
  import {SharedElement} from 'navigation-react-native';
  import ZoomShared from './ZoomShared';
  @@ -8,18 +8,38 @@ export default class Detail extends React.Component {
  super(props, context);
  const {url} = props.stateNavigator.stateContext;
  this.url = url;
  + this.state = {
  + contentAnimation: new Animated.Value(0),
  + navbarAnimation: new Animated.Value(0),
  + };
  }
  shouldComponentUpdate(props) {
  return this.url === props.stateNavigator.stateContext.url;
  }
  + componentDidMount() {
  + Animated.timing(this.state.contentAnimation, {
  + toValue: 1,
  + duration: 500,
  + useNativeDriver: true,
  + }).start();
  + }
  _goBack = () => {
  const {stateNavigator} = this.props;
  if (this.url === stateNavigator.stateContext.url) {
  stateNavigator.navigateBack(1);
  + Animated.timing(this.state.contentAnimation, {
  + toValue: 0,
  + duration: 500,
  + useNativeDriver: true,
  + }).start();
  }
  };
  render() {
  const {place, stateNavigator} = this.props;
  + const contentTranslateY = this.state.contentAnimation.interpolate({
  + inputRange: [0, 1],
  + outputRange: [200, 0],
  + });
  return (
  <View style={{ flex: 1 }}>
  <ScrollView style={{ flex: 1 }}>
  @@ -48,9 +68,10 @@ export default class Detail extends React.Component {
  <Text style={styles.title} numberOfLines={1}>{place.title}</Text>
  <View style={styles.placeholder} />
  </View>
  - <View>
  + <Animated.View
  + style={{ transform: [{ translateY: contentTranslateY }] }}>
  <Text style={styles.descriptionText}>{place.description}</Text>
  - </View>
  + </Animated.View>
  </View>
  </ScrollView>
  </View>
  