分享一个box-shadow阴影组件封装，可自动适应内容宽高。
首先要安装react-native-shadow
yarn add react-native-shadow
然后安装一个react-native-svg，注意要去github上看下版本对照表，要对应版本安装
yarn add react-native-svg/yarn add react-native-svg@x.x.x

封装：

import React from 'react'
import {
  ViewStyle
} from 'react-native'
import Base from '@/components/Base';
import { View } from '@/components';
import { BoxShadow as RNBoxShadow, BoxShadowType } from "react-native-shadow";

interface Props {
  data?: any   //用来控制重新渲染高度
  style?: ViewStyle
  color?: string
  shadowOption?: {
    border?: number;    // the width of shadow , cannot less than 0
    radius?: number;    // the same value as the "borderRadius" of chileElement
    opacity?: number;   // the opacity of shadow
    x?: number;         // the offsetX of shadow
    y?: number;         // the offsetY of shadow
    style?: ViewStyle;     // the style you want to add to the wrapper box
  }
  children?: React.ReactNode;
}

interface State {
  contentHeight: number
  contentWidth: number
  showShadow: boolean
}
/**
 * box-shadow组件，包裹在需要阴影的View外
 * @param {string} color  阴影颜色
 * @param {Object} shadowOption  阴影配置
 * @param {*} data  触发重新渲染的props,用来重新计算宽高
 * **/
export default class BoxShadow extends Base<Props, State> {

  public state: State = {
    contentHeight: 0,
    contentWidth: 0,
    showShadow: false
  };


  public componentDidMount() {

  }

  public componentWillReceiveProps(nextProps:any) {
    if(nextProps.hasOwnProperty('data') && 
      JSON.stringify(this.props.data) != JSON.stringify(nextProps.data)
    ) {
      // reRender
      this.setState({
        showShadow: false
      })
    }
  }

  render() {
    const { color, style, shadowOption } = this.props;

    if (!this.state.showShadow) {
      return (
        <View style={style}
          onLayout={e => {
            const layout = e.nativeEvent.layout
            // console.log(layout)
            this.setState({
              contentWidth: layout.width,
              contentHeight: layout.height,
              showShadow: true
            })
          }}
        >
          {this.props.children}
        </View>
      )
    }

    return (
      <RNBoxShadow
        setting={{
          height: this.state.contentHeight,
          width: this.state.contentWidth,
          color: color || '#000',
          border: shadowOption?.border || 5,
          radius: shadowOption?.radius || 5,
          opacity: shadowOption?.opacity || 0.2,
          x: shadowOption?.x || 0,
          y: shadowOption?.y || 0,
          style: shadowOption?.style || {},
        }}
      >
        <View style={style}>
          {this.props.children}
        </View>
      </RNBoxShadow>
    );
  }
}
export { BoxShadow };

使用：

import { BoxShadow, View, Text } from "@/components";

//...
render() {
  const { info } = this.state
  return (
    <BoxShadow data={info} shadowOption={{
      border: 10,
      opacity: 0.5
    }}>
      <View style={{backgroundColor: '#fff'}}>
       <Text>{info}</Text>
      </View>
    </BoxShadow>
  )
}