城市列表选择是很多app共有的功能，比如典型的美图app。那么对于React Native怎么实现呢？

要实现上面的效果，首先需要对界面的组成简单分析，界面的数据主要由当前城市，历史访问城市和热门城市组成，所以我们在提供Json数据的时候就需要将数据分为至少3部分。

const ALL_CITY_LIST = DATA_JSON.allCityList;
const HOT_CITY_LIST = DATA_JSON.hotCityList;
const LAST_VISIT_CITY_LIST = DATA_JSON.lastVisitCityList;

而要实现字母索引功能，我们需要自定义一个控件，实现和数据的绑定关系，自定义组件代码如下：

CityIndexListView.js

'use strict';
import React, {Component} from 'react';
import {
 StyleSheet,
 View,
 Text,
 TouchableOpacity,
 ListView,
 Dimensions,
} from 'react-native';

import Toast, {DURATION} from './ToastUtil'

const SECTIONHEIGHT = 30;
const ROWHEIGHT = 40;
const ROWHEIGHT_BOX = 40;
var totalheight = []; //每个字母对应的城市和字母的总高度

const {width, height} = Dimensions.get('window');

var that;

const key_now = '当前';
const key_last_visit = '最近';
const key_hot = '热门';

export default class CityIndexListView extends Component {

 constructor(props) {
 super(props);

 var getSectionData = (dataBlob, sectionID) => {
 return sectionID;
 };
 var getRowData = (dataBlob, sectionID, rowID) => {
 return dataBlob[sectionID][rowID];
 };

 let ALL_CITY_LIST = this.props.allCityList;
 let CURRENT_CITY_LIST = this.props.nowCityList;
 let LAST_VISIT_CITY_LIST = this.props.lastVisitCityList;
 let HOT_CITY_LIST = this.props.hotCityList;

 let letterList = this._getSortLetters(ALL_CITY_LIST);

 let dataBlob = {};
 dataBlob[key_now] = CURRENT_CITY_LIST;
 dataBlob[key_last_visit] = LAST_VISIT_CITY_LIST;
 dataBlob[key_hot] = HOT_CITY_LIST;

 ALL_CITY_LIST.map(cityJson => {
 let key = cityJson.sortLetters.toUpperCase();

 if (dataBlob[key]) {
 let subList = dataBlob[key];
 subList.push(cityJson);
 } else {
 let subList = [];
 subList.push(cityJson);
 dataBlob[key] = subList;
 }
 });

 let sectionIDs = Object.keys(dataBlob);
 let rowIDs = sectionIDs.map(sectionID => {
 let thisRow = [];
 let count = dataBlob[sectionID].length;
 for (let ii = 0; ii < count; ii++) {
 thisRow.push(ii);
 }

 let eachheight = SECTIONHEIGHT + ROWHEIGHT * thisRow.length;
 if (sectionID === key_hot || sectionID === key_now || sectionID === key_last_visit) {
 let rowNum = (thisRow.length % 3 === 0)
 ? (thisRow.length / 3)
 : parseInt(thisRow.length / 3) + 1;

 console.log('sectionIDs===>' + sectionIDs + ", rowNum=====>" + rowNum);

 eachheight = SECTIONHEIGHT + ROWHEIGHT_BOX * rowNum;
 }

 totalheight.push(eachheight);

 return thisRow;
 });


 let ds = new ListView.DataSource({
 getRowData: getRowData,
 getSectionHeaderData: getSectionData,
 rowHasChanged: (row1, row2) => row1 !== row2,
 sectionHeaderHasChanged: (s1, s2) => s1 !== s2
 });

 this.state = {
 dataSource: ds.cloneWithRowsAndSections(dataBlob, sectionIDs, rowIDs),
 letters: sectionIDs
 };

 that = this;
 }

 _getSortLetters(dataList) {
 let list = [];

 for (let j = 0; j < dataList.length; j++) {
 let sortLetters = dataList[j].sortLetters.toUpperCase();

 let exist = false;
 for (let xx = 0; xx < list.length; xx++) {
 if (list[xx] === sortLetters) {
 exist = true;
 }
 if (exist) {
 break;
 }
 }
 if (!exist) {
 list.push(sortLetters);
 }
 }

 return list;
 }

 _cityNameClick(cityJson) {
 // alert('选择了城市====》' + cityJson.id + '#####' + cityJson.name);
 this.props.onSelectCity(cityJson);
 }

 _scrollTo(index, letter) {
 this.refs.toast.close();
 let position = 0;
 for (let i = 0; i < index; i++) {
 position += totalheight[i]
 }
 this._listView.scrollTo({y: position});
 this.refs.toast.show(letter, DURATION.LENGTH_SHORT);
 }

 _renderRightLetters(letter, index) {
 return (
 <TouchableOpacity key={'letter_idx_' + index} activeOpacity={0.6} onPress={() => {
 this._scrollTo(index, letter)
 }}>
 <View style={styles.letter}>
 <Text style={styles.letterText}>{letter}</Text>
 </View>
 </TouchableOpacity>
 );
 }

 _renderListBox(cityJson, rowId) {
 return (
 <TouchableOpacity key={'list_item_' + cityJson.id} style={styles.rowViewBox} onPress={() => {
 that._cityNameClick(cityJson)
 }}>
 <View style={styles.rowdataBox}>
 <Text style={styles.rowDataTextBox}>{cityJson.name}</Text>
 </View>
 </TouchableOpacity>
 );
 }

 _renderListRow(cityJson, rowId) {
 console.log('rowId===>' + rowId + ", cityJson====>" + JSON.stringify(cityJson));
 if (rowId === key_now || rowId === key_hot || rowId === key_last_visit) {
 return that._renderListBox(cityJson, rowId);
 }

 return (
 <TouchableOpacity key={'list_item_' + cityJson.id} style={styles.rowView} onPress={() => {
 that._cityNameClick(cityJson)
 }}>
 <View style={styles.rowdata}>
 <Text style={styles.rowdatatext}>{cityJson.name}</Text>
 </View>
 </TouchableOpacity>
 )
 }

 _renderListSectionHeader(sectionData, sectionID) {
 return (
 <View style={styles.sectionView}>
 <Text style={styles.sectionText}>
 {sectionData}
 </Text>
 </View>
 );
 }

 render() {
 return (
 <View style={styles.container}>
 <View style={styles.listContainner}>
 <ListView ref={listView => this._listView = listView}
 contentContainerStyle={styles.contentContainer} dataSource={this.state.dataSource}
 renderRow={this._renderListRow} renderSectionHeader={this._renderListSectionHeader}
 enableEmptySections={true} initialListSize={500}/>
 <View style={styles.letters}>
 {this.state.letters.map((letter, index) => this._renderRightLetters(letter, index))}
 </View>
 </View>
 <Toast ref="toast" position='top' positionValue={200} fadeInDuration={750} fadeOutDuration={1000}
 opacity={0.8}/>
 </View>
 )
 }
}

const styles = StyleSheet.create({
 container: {
 // paddingTop: 50,
 flex: 1,
 flexDirection: 'column',
 backgroundColor: '#F4F4F4',
 },
 listContainner: {
 height: Dimensions.get('window').height,
 marginBottom: 10
 },
 contentContainer: {
 flexDirection: 'row',
 width: width,
 backgroundColor: 'white',
 justifyContent: 'flex-start',
 flexWrap: 'wrap'
 },
 letters: {
 position: 'absolute',
 height: height,
 top: 0,
 bottom: 0,
 right: 10,
 backgroundColor: 'transparent',
 // justifyContent: 'flex-start',
 // alignItems: 'flex-start'
 alignItems: 'center',
 justifyContent: 'center'
 },
 letter: {
 height: height * 4 / 100,
 width: width * 4 / 50,
 justifyContent: 'center',
 alignItems: 'center'
 },
 letterText: {
 textAlign: 'center',
 fontSize: height * 1.1 / 50,
 color: '#e75404'
 },
 sectionView: {
 paddingTop: 5,
 paddingBottom: 5,
 height: 30,
 paddingLeft: 10,
 width: width,
 backgroundColor: '#F4F4F4'
 },
 sectionText: {
 color: '#e75404',
 fontWeight: 'bold'
 },
 rowView: {
 height: ROWHEIGHT,
 paddingLeft: 10,
 paddingRight: 10,
 borderBottomColor: '#F4F4F4',
 borderBottomWidth: 0.5
 },
 rowdata: {
 paddingTop: 10,
 paddingBottom: 2
 },

 rowdatatext: {
 color: 'gray',
 width: width
 },

 rowViewBox: {
 height: ROWHEIGHT_BOX,
 width: (width - 30) / 3,
 flexDirection: 'row',
 backgroundColor: '#ffffff'
 },
 rowdataBox: {
 borderWidth: 1,
 borderColor: '#DBDBDB',
 marginTop: 5,
 marginBottom: 5,
 paddingBottom: 2,
 marginLeft: 10,
 marginRight: 10,
 flex: 1,
 justifyContent: 'center',
 alignItems: 'center'
 },
 rowDataTextBox: {
 marginTop: 5,
 flex: 1,
 height: 20
 }

});
 

然后在头部还需要实现一个搜索框。

SearchBox.js

'use strict';
import React, {Component} from 'react';
import {
 View,
 TextInput,
 StyleSheet,
 Platform,
} from 'react-native';

export default class SearchBox extends Component {
 constructor(props) {
 super(props);
 this.state = {
 value: ''
 };

 }

 onEndEditingKeyword(vv) {
 console.log(vv);
 }

 onChanegeTextKeyword(vv) {
 console.log('onChanegeTextKeyword', vv);

 this.setState({value: vv});
 this.props.onChanegeTextKeyword(vv);
 }

 render() {
 return (
 <View style={styles.container}>
 <View style={styles.inputBox}>
 <View style={styles.inputIcon}>
 </View>
 <TextInput ref="keyword" autoCapitalize="none" value={this.props.keyword}
 onChangeText={this.onChanegeTextKeyword.bind(this)} returnKeyType="search" maxLength={20}
 style={styles.inputText} underlineColorAndroid="transparent"
 placeholder={'输入城市名或拼音查询'}/>
 </View>
 </View>
 )
 }
}

const styles = StyleSheet.create({
 container: {
 marginTop: 5,
 marginBottom: 5,
 backgroundColor: '#ffffff',
 flexDirection: 'row',
 height: Platform.OS === 'ios'
 ? 35
 : 45,
 borderBottomWidth: StyleSheet.hairlineWidth,
 borderBottomColor: '#cdcdcd',
 paddingBottom: 5
 },
 inputBox: {
 height: Platform.OS === 'ios'
 ? 30
 : 40,
 marginLeft: 5,
 marginRight: 5,
 flex: 1,
 flexDirection: 'row',
 backgroundColor: '#E6E7E8'
 },
 inputIcon: {
 margin: Platform.OS === 'ios'
 ? 5
 : 10
 },
 inputText: {
 alignSelf: 'flex-end',
 marginTop: Platform.OS === 'ios'
 ? 0
 : 0,
 flex: 1,
 height: Platform.OS === 'ios'
 ? 30
 : 40,
 marginLeft: 2,
 marginRight: 5,
 fontSize: 12,
 lineHeight: 30,
 textAlignVertical: 'bottom',
 textDecorationLine: 'none'
 }
});

最终效果：

最后是界面的绘制，这里就不多说了，大家可以下载源码自行查看。源码地址：react-native-city_jb51.rar