App.js

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */
// 參考 https://medium.com/react-native-training/react-native-animations-using-the-animated-api-ebe8e0669fae
import React, { Component } from 'react';
import {
  Platform,
  StyleSheet,
  Text,
  View,
  Animated,
  Easing
} from 'react-native';
import Router from './src/Router';

const instructions = Platform.select({
  ios: 'Press Cmd+R to reload,\n' +
    'Cmd+D or shake for dev menu',
  android: 'Double tap R on your keyboard to reload,\n' +
    'Shake or press menu button for dev menu',
});

type Props = {};
export default class App extends Component<Props> {
  constructor(props) {
    super(props);
    this.spinValue = new Animated.Value(0);
  }

  componentDidMount () {
    this.spin()
  }
  spin = () => {
    this.spinValue.setValue(0);
    Animated.timing(
      this.spinValue,
      {
        toValue: 1,
        duration: 4000,
        easing: Easing.linear
      }
    ).start(() => this.spin());
  }

  render() {
    const spin = this.spinValue.interpolate({
      inputRange: [0, 1],
      outputRange: ['0deg', '360deg']
    });

    return (
      <Router />
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,
  },
});