React Native动画组件Animated-----案例

import React, { Component } from 'react'
import { View, StyleSheet, Animated, TouchableOpacity } from 'react-native'

class App extends Component {
    //为什么要使用UNSAFE_componentWillMount，因为componentWillMount要废弃
   UNSAFE_componentWillMount = () => {
      //创建动画属性对象
      this.animatedWidth = new Animated.Value(50)
      this.animatedHeight = new Animated.Value(100)
   }
   animatedBox = () => {
      //点击后，设置动画变化
      Animated.timing(this.animatedWidth, {
         toValue: 200,
         duration: 1000
      }).start()
      Animated.timing(this.animatedHeight, {
         toValue: 500,
         duration: 500
      }).start()
   }
   render() {
      const animatedStyle = {
            width: this.animatedWidth, 
            height: this.animatedHeight }
      return (
         <TouchableOpacity 
            style = {styles.container} 
            onPress = {this.animatedBox}>
            <Animated.View style = {[styles.box, animatedStyle]}/>
         </TouchableOpacity>
      )
   }
}
export default App

const styles = StyleSheet.create({
   container: {
      justifyContent: 'center',
      alignItems: 'center'
   },
   box: {
      backgroundColor: 'blue',
      width: 50,
      height: 100
   }
})