在原生APP开发中，相信很多开发者都会见到这种场景：点击右上角更多的选项，弹出一个更多界面供用户选择。这种控件在原生开发中Android可以用PopupWindow实现，在iOS中可以用CMPopTipView,也可以自己写一个View实现。其类似的效果如下图所示：

实现思路分析：

要实现上面的视图，有很多种实现方式。前面的文章说过，要实现弹框相关的可以用React Native 提供的 Modal组件(Modal组件)，使用Modal组件可以实现我们原生开发中的大多数效果。

要实现下拉三角，可以让美工切一个带下拉三角的背景，当然也可以自己通过ART实现（ART绘制）。对于选项卡的内容，在原生开发中为了适应更多的场景，我们一般会选择使用ListView组件，然后当点击某个Item的时候获得相应的属性即可。为了控制Modal的显示与消失，我们可以给Modal内置一个isVisible: this.props.show状态。

源码

要实现上面的效果，会这涉及到三个js文件：MorePopWidows.js、Utils.js、HomeActionBar.js，按照先后顺序，代码如下：

Utils.js

import {Dimensions} from 'react-native'

const deviceH = Dimensions.get('window').height
const deviceW = Dimensions.get('window').width

const basePx = 375

export default function px2dp(px) { 
 return px * deviceW / basePx
}

MorePopWidows.js

import React from 'react'
import {
 StyleSheet,
 Platform,
 View,
 Text,
 Image,
 TouchableOpacity,
 Alert,
 Modal,
 Dimensions,
} from 'react-native'
import SpacingView from "./SpacingView";
import QRScanPage from "../home/QRScanPage";

const { width, height } = Dimensions.get('window');
import px2dp from '../util/Utils'

const mTop = px2dp(Platform.OS == "ios" ?  : 44)

let mwidth = 95;
let mheight = 100;
const marginTop = mTop;

export default class MorePopWidows extends React.Component {

 constructor(props) {
 super(props);
 this.state = {
 isVisible: this.props.show,
 }
 mwidth = this.props.width ;
 mheight = this.props.height ;
 }

 componentWillReceiveProps(nextProps) {
 this.setState({ isVisible: nextProps.show });
 }

 closeModal() {
 this.setState({
 isVisible: false
 });
 this.props.closeModal(false);
 }

 scan() {
 this.props.navigator.push({
 component: QRScanPage,
 })
 }

 render() {
 return (
 <View style={styles.container}>
 <Modal
 transparent={true}
 visible={this.state.isVisible}
 animationType={'fade'}
 onRequestClose={() => this.closeModal()}>
 <TouchableOpacity style={styles.container} activeOpacity={1} onPress={() => this.closeModal()}>

 <View style={styles.modal}>
 <TouchableOpacity activeOpacity={1} onPress={this.scan.bind(this)} style={styles.itemView}>
 <Image style={styles.imgStyle} source={require('../images/ic_scan_code_white.png')} />
 <Text style={styles.textStyle}>扫一扫</Text>
 </TouchableOpacity>
 <SpacingView/>
 <TouchableOpacity activeOpacity={1} onPress={() => Alert.alert('点击了付款码')} style={styles.itemView}>
 <Image style={styles.imgStyle} source={require('../images/ic_code_white.png')} />
 <Text style={styles.textStyle}>付款码</Text>
 </TouchableOpacity>
 </View>
 </TouchableOpacity>
 </Modal>
 </View>
 )
 }
}
const styles = StyleSheet.create({
 container: {
 width: width,
 height: height,
 },
 modal: {
 backgroundColor: '#696969',
 width: mwidth,
 height: mheight,
 position: 'absolute',
 left: width - mwidth - 10,
 top: marginTop,
 padding: 5,
 justifyContent: 'center',
 alignItems: 'center',
 borderRadius: 3,
 },
 itemView: {
 flexDirection: 'row',
 justifyContent: 'center',
 alignItems: 'center',
 flex: 1,
 },
 textStyle: {
 color: '#fff',
 fontSize: 14,
 marginLeft: 2,
 },
 imgStyle: {
 width: 20,
 height: 20,
 }
});

最后是在代码中使用MorePopWidows的代码：

HomeActionBar.js

/**
 * https://github.com//react-native
 * @flow 首页的标题栏
 */

import React, {Component} from 'react';
import {Platform, View, Dimensions, Text, StyleSheet, TouchableOpacity, Image} from 'react-native';
import SelectCityPage from '../home/SelectCityPage'
import MorePopWidows from '../component/MorePopWidows'
import px2dp from '../util/Utils'

const isIOS = Platform.OS == "ios"
const {width, height} = Dimensions.get('window')
const headH = px2dp(isIOS ?  : 44)

export default class HomeActionBar extends Component {

 constructor(props) {
 super(props);
 this.state = {
 showPop: false,
 }
 }

 city() {
 this.props.navigator.push({
 component: SelectCityPage,
 })
 }

 renderHeader() {
 return (
 <View >
 <View style={styles.headerStyle}>
 <TouchableOpacity style={styles.action} onPress={this.city.bind(this)}>
 <Text style={styles.text}>上海</Text>
 <Image
 source={require('../images/ic_arrow_down.png')}/>
 </TouchableOpacity>
 <TouchableOpacity style={styles.searchBar}>
 <Image source={require('../images/ic_search.png')} style={styles.iconStyle}/>
 <Text style={{fontSize: 13, color: "#666", marginLeft: 5}}>输入商家、商品名称</Text>
 </TouchableOpacity>
 <TouchableOpacity style={styles.action} onPress={() => { this.setState({ showPop: !this.state.showPop }) }}>
 <Image style={styles.scanIcon}
 source={require('../images/ic_scan_code_white.png')}/>
 <Text style={styles.scanText}>扫码</Text>
 </TouchableOpacity>
 </View>
 <View style={{ position: 'absolute', top: headH, left: 0, width: width, height: height }}>
 <MorePopWidows width={90} height={100} show={this.state.showPop} closeModal={(show) => {
 this.setState({showPop: show})
 }} {...this.props}/>
 </View>

 </View>
 )
 }

 render() {
 return (
 <View>
 {this.renderHeader()}
 </View>
 );
 }
}

const styles = StyleSheet.create({
 headerStyle: {
 backgroundColor: "#06C1AE",
 height: headH,
 paddingTop: px2dp(isIOS ? 20 : 0),
 paddingHorizontal: 16,
 flexDirection: 'row',
 alignItems: 'center',
 },
 searchBar: {
 width: width * 0.65,
 height: 30,
 borderRadius: 19,
 marginLeft: 10,
 flexDirection: 'row',
 justifyContent: 'flex-start',
 alignItems: 'center',
 backgroundColor: 'white',
 alignSelf: 'center',
 paddingLeft: 10,
 },
 text: {
 fontSize: 16,
 color: '#ffffff',
 justifyContent: 'center',
 },
 iconStyle: {
 width: 22,
 height: 22,
 },
 action: {
 flexDirection: 'row',
 justifyContent: 'center',
 alignItems: 'center',
 },
 scanIcon: {
 width: 28,
 height: 28,
 alignItems: 'center',
 marginLeft: 10,
 },
 scanText: {
 fontSize: 14,
 color: '#ffffff',
 justifyContent: 'center',
 alignItems: 'center',
 },
});