Animation dans ActivityIndicator

import React, { Component } from 'react';
import {
  Text,
  View,
  StyleSheet,
  TextInput,
  TouchableHighlight,
  ActivityIndicator
} from 'react-native';

export class Login extends Component {

    constructor(props) {
        super(props);

        this.state = {
            showProgress: false
        };
    }

    render() {
        return (
            <View>

                <TouchableHighlight onPress={this.progressOff.bind(this)}>
                    <Text>progressOff</Text>
                </TouchableHighlight>

                <TouchableHighlight onPress={this.progressOn.bind(this)}>
                    <Text>progressOn</Text>
                </TouchableHighlight>

                <ActivityIndicator animating={this.state.showProgress} size="large"/>
            </View>
        );
    }

    progressOff() {
        this.setState({showProgress: false}); 
    }

    progressOn() {
        this.setState({showProgress: true});
    }
}
Helpless Hippopotamus