Rn实现省市区三级联动

省市区三级联动选择是个很频繁的需求，但是查看了市面上很多插件不是太老不维护就是不满足需求，就试着实现一个
这个功能无任何依赖插件
功能略简单，但能实现需求
核心代码也尽力控制在了60行左右
pca-code.json树型数据来源 Administrative-divisions-of-China
下面只贴了省市区选择的功能，全部代码可参考github area分支

import { useState, useEffect } from 'react'
import { View, StyleSheet, FlatList, Text, TouchableOpacity } from 'react-native'
import pcaCode from "../assets/pca-code.json"export default () => {const [selected, setSelected] = useState([]) //选择过的省市区const [options, setOptions] = useState([pcaCode]) //每一级的数据const [level, setLevel] = useState(0) // 当前展示第几级useEffect(() => {console.log(selected)}, [selected])const renderItem = ({ item }) => (<TouchableOpacity style={styles.option} onPress={() => activeItem(item)}><Text style={[styles.option_text, isActive(item.code) && styles.option_text_active]}>{item.name}</Text>{isActive(item.code) && <View style={styles.option_icon} />}</TouchableOpacity >)const isActive = (code) => selected.some(item => item.code == code)const activeItem = (item) => {setSelected((prev) => {const newSelected = [...prev]newSelected[level] = { code: item.code, name: item.name }return newSelected.slice(0, level + 1)})if (level < 2) {const nextLevel = level + 1setLevel(nextLevel)setOptions((prev) => {const nextOptions = [...prev]nextOptions[nextLevel] = item.childrenreturn nextOptions})}}const PanelTab = () => {const tabs = selected.length < 3 ? selected.concat({ name: "请选择" }) : selectedreturn (<View style={styles.tab}>{tabs.map((item, index) => {return (<View style={styles.tab_item} key={index}><TouchableOpacity onPress={() => setLevel(index)}><Text style={item.code ? styles.tab_item_text : styles.tab_item_text_gray}>{item.name}</Text></TouchableOpacity>{level == index && <View style={styles.tab_item_line} />}</View>)})}</View>)}return (<><PanelTab /><FlatList style={styles.flat} data={options[level]} renderItem={renderItem} keyExtractor={item => item.code} /></>)
}const styles = StyleSheet.create({flat: {height: 500,},option: {height: 40,paddingRight: 15,flexDirection: "row",alignItems: "center",justifyContent: "space-between",},option_text: {fontSize: 14},option_text_active: {color: "#409eff",fontWeight: 'bold',},option_icon: {width: 6,height: 10,borderBottomWidth: 2,borderBottomColor: "#409eff",borderRightWidth: 2,borderRightColor: "#409eff",transform: "rotate(45deg)"},tab: {flexDirection: "row",marginBottom: 10,},tab_item: {position: "relative",marginRight: 15,},tab_item_text: {fontSize: 14,fontWeight: 'bold',paddingBottom: 10,},tab_item_text_gray: {fontSize: 14,color: "gray",paddingBottom: 10,},tab_item_line: {position: "absolute",bottom: 0,left: 0,width: "100%",height: 3,borderRadius: 5,backgroundColor: "#409eff"}
})