如何在 FlatList 中选择多个项目，突出显示它们并将它们保存在 React Native 中

Question

I want to select multiple items from the FlatList. Whenever, I click them, they should be highlighted and they should be saved in some state variable

I am using 'react-native-android-installed-apps' to get a list of all the installed apps in a FLatList

This is what I have done up till now:

import React, {Component} from 'react';
import {View, Text, Image, FlatList, Dimensions, TouchableOpacity} from 'react-native';
import RNAndroidInstalledApps from 'react-native-android-installed-apps';

class App extends Component {
    constructor(props) {
        super(props);

        this.state = {
            data: []
        };
    }

    componentDidMount() {
        this.check();
    }

    check = () => {
        let combine = [];
        RNAndroidInstalledApps.getApps()
            .then(apps => {
                if(apps.length > 0) {
                    for(let i = 0; i< apps.length ; i++) {
                        thisApp = apps[i];
                        const obj = {'appName': thisApp.appName, 'icon': thisApp.icon};
                        combine.push(obj);
                    }
                }
                this.setState({
                    data: combine
                });
                // console.log(this.state.data);
            });
    };

    renderSeperator = () => {
        return(
            <View
                style={{
                    height: 1,
                    backgroundColor: '#CED0CE',
                }}
            />
        );
    };

    render() {
        return(
        <FlatList
                data={this.state.data}
                renderItem={({ item }) =>(
                    <TouchableOpacity
                        style={{flexDirection:'row', padding: 5 }}
                    >
                        <Image
                            style={{width: 51, height: 51, resizeMode: 'contain', flex: 1 }}
                            source={{ uri: `data:image;base64,${item.icon}` }}
                        />
                        <Text style={{alignSelf: 'center', marginStart: 10, flex: 5 }}>{item.appName}</Text>
                    </TouchableOpacity>
                )}
                keyExtractor={(item) => item.appName}
                ItemSeparatorComponent={this.renderSeperator}
        />
        );
    }
}

export default App;

I expect to highlight each item when it is selected, and save it's data in some state variable

Answer 1

Let's do this with some array checkList and we put it inside state, the FlatList look like this:

<FlatList
     data={this.state.data}
     renderItem={({ item }) =>(
    <TouchableOpacity
    onPress={()=>{
      const list = this.state.checkList; 
      list.push(item)
      this.setState({checkList: list})
    }}
    style={{flexDirection:'row', padding: 5 }} >
  <Image
       style={{width: 51, height: 51, resizeMode: 'contain', flex: 1 }}
       source={{ uri: `data:image;base64,${item.icon}` }}
      />
  <Text style={{alignSelf: 'center', marginStart: 10, flex: 5 }}>{item.appName}</Text>
       </TouchableOpacity>
           )}
           keyExtractor={(item) => item.appName}
           ItemSeparatorComponent={this.renderSeperator}
        />

this way you save all item that clicked, you can develop it more and drop from the list when it clicked again or change color for the check list

Answer 2

Figured it out:

import React, {Component} from 'react';
import {View, Text, Image, FlatList, TouchableOpacity} from 'react-native';
import RNAndroidInstalledApps from 'react-native-android-installed-apps';

var selected = [];
class App extends Component {
    constructor(props) {
        super(props);

        this.state = {
            data: [],
            itemChecked: []
        };
    }

    componentDidMount() {
        this.check();
    }

    check = () => {
        let combine = [];
        RNAndroidInstalledApps.getApps()
            .then(apps => {
                if(apps.length > 0) {
                    for(let i = 0; i< apps.length ; i++) {
                        thisApp = apps[i];
                        const obj = {'appName': thisApp.appName, 'icon': thisApp.icon, 'isSelect': false};
                        combine.push(obj);
                    }
                }
                this.setState({
                    data: combine
                });
                // console.log(this.state.data);
            });
    };

    renderSeperator = () => {
        return(
            <View
                style={{
                    height: 1,
                    backgroundColor: '#CED0CE',
                }}
            />
        );
    };

    selectItem = (item) => {
        item.isSelect = !item.isSelect;
        if(item.isSelect){
            selected.push(item.appName);
        } else {
            for(let i = 0; i < selected.length; i++) {
                if(selected[i] === item.appName) {
                    selected.splice(i, 1)
                }
            }
        }
        this.setState({itemChecked: selected});
    };

    renderRow = (item) => {
        const isSelected = item.isSelect;
        const viewStyle = isSelected ? styles.selected : styles.normal;
        return(
            <TouchableOpacity
                style={viewStyle}
                onPress={() => this.selectItem(item)}
            >
                <Image
                    style={{width: 51, height: 51, resizeMode: 'contain', flex: 1 }}
                    source={{ uri: `data:image;base64,${item.icon}` }}
                />
                <Text style={{alignSelf: 'center', marginStart: 10, flex: 5 }}>{item.appName}</Text>
            </TouchableOpacity>
        );
    };

    render() {
        return(
        <FlatList
                data={this.state.data}
                renderItem={({item}) => this.renderRow(item)}
                keyExtractor={(item) => item.appName}
                ItemSeparatorComponent={this.renderSeperator}
                extraData={this.state}
        />
        );
    }
}

const styles = {
    selected: {
        flexDirection: 'row',
        padding: 5,
        backgroundColor: 'blue'
    },
    normal: {
        flexDirection: 'row',
        padding: 5
    }    
}

export default App;

Answer 3

For that, you can use the library react-native-sectioned-multi-select

Documentation in https://github.com/renrizzolo/react-native-sectioned-multi-select