无法在React Native中执行变换动画

无法获取 Animated 工作。我正在添加按钮样式和 Animated.View 在容器中。所以当我 pressIn 我想要 有生气的看法 缩小到0.5,启用时 pressOut 希望它返回到1。我设置了 this.animatedValue = new Animated.Value(1) 在…上 componentWillMount 它本身我的代码如下:

'use strict';

import React, { Component } from 'react';
import { StyleSheet, Text, Animated, Easing, Image,
         TouchableWithoutFeedback, View} from 'react-native';

class MyAnim extends Component {
    constructor(props) {
      super(props);
      this.state = {};
      this.handlePressIn = this.handlePressIn.bind(this);
      this.handlePressOut = this.handlePressOut.bind(this);
    }

  componentWillMount() {
    this.animatedValue = new Animated.Value(1);
  }

  handlePressIn() {
    Animated.spring(this.animatedValue,{
        to: .5
    }).start()
  }
  handlePressOut() {
    Animated.spring(this.animatedValue,{
        to: 1,
        friction: 3,
        tension: 40
    }).start()
  }

  render() {
    const animatedStyle = {
        transform: [{ scale: this.animatedValue }]
    }
    return (
      <View style={styles.container}>
        <TouchableWithoutFeedback
          onPressIn={this.handlePressIn}
          onPressOut={this.handlePressOut}
        >
          <Animated.View style={[styles.button, animatedStyle]}>
            <Text style={styles.buttonText}>Press Me</Text>
          </Animated.View>
        </TouchableWithoutFeedback>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container:{
    flex:1, justifyContent:'center', alignItems:'center'
  },
  button:{
    backgroundColor:'#333', width:100, height:50, marginBottom:10,
    justifyContent:'center', alignItems:'center'
  },
  buttonText:{
    color:'#fff'
  },
});

export default MyAnim;

我正在尝试一个简单的春季动画。错误是:

我做错了什么?我希望按钮转换为大小。按入时为5,按出时为1。