show 2 items per row[react native]

问题:

I am learning react native and in all the tutorials i see ListView has been used with only 1 items per row. I have not used ListView, though. I have only 6 items that has to be shown as flat grid with 2 items per row and should be responsive. I know its a basic question, but i have tried from my side too which can be seen in the image

This is my code

 renderDeviceEventList() {
    return _.map(this.props.deviceEventOptions, deviceEventOption => (
        <View key={deviceEventOption.id}>
            <Icon
                name={deviceEventOption.icon_name}
                color="#ddd"
                size={30}
                onPress={() =>
                    this.props.selectDeviceEvent(deviceEventOption)
                }
            />
            <Text style={{ color: "#ff4c4c" }}>
                {deviceEventOption.icon_name}
            </Text>
        </View>
    ));
}
render() {
    return (
        <View
            style={{
                flex: 1,
                top: 60,
                flexDirection: "row",
                justifyContent: "space-around",
                flexWrap: "wrap",
                marginBottom: 10
            }}
        >
            {this.renderDeviceEventList()}
        </View>
    );
}

回答1:

To make a 2 row grid using ListView you could use this code as an example:

renderGridItem( item ){
    return (<TouchableOpacity style={styles.gridItem}>
        <View style={[styles.gridItemImage, justifyContent:'center', alignItems:'center'}]}>
            <Text style={{fontSize:25, color:'white'}}>
                {item.fields.name.charAt(0).toUpperCase()}
            </Text>
        </View>
        <Text style={styles.gridItemText}>{item.fields.name}</Text> 
    </TouchableOpacity>
    );
}

renderCategories(){

    var listItems = this.dsinit.cloneWithRows(this.state.dataSource);

    return (
        <ScrollView style={{backgroundColor: '#E8E8E8', flex: 1}} >
            <ListView 
                contentContainerStyle={styles.grid}
                dataSource={listItems}
                renderRow={(item) => this.renderGridItem(item)}
            />
        </ScrollView>
    );
}

const styles = StyleSheet.create({
    grid: {
        justifyContent: 'center',
        flexDirection: 'row',
        flexWrap: 'wrap',
        flex: 1,
    },
    gridItem: {
        margin:5,
        width: 150,
        height: 150,
        justifyContent: 'center',
        alignItems: 'center',
    },
    gridItemImage: {
        width: 100,
        height: 100,
        borderWidth: 1.5, 
        borderColor: 'white',
        borderRadius: 50,
    },
    gridItemText: {
        marginTop: 5,
        textAlign:'center',
    },
});

Change styles to choose how many rows you want to see on screen. This code is responsive.

回答2:

You can try the flat list from react native. where in you can specific the number of columns and also can mention the vertical direction or horizontal direction. Sample code:

<FlatList
data={this.props.data}
keyExtractor={this._keyExtractor}     //has to be unique   
renderItem={this._renderItem} //method to render the data in the way you want using styling u need
horizontal={false}
numColumns={2}
          />

Refer https://facebook.github.io/react-native/docs/flatlist.html for more.

回答3:

The correct way to do it would be with flexBasis, with a value set to (1/n)% where n is the desired # of rows > 0. For two rows:

.parent {
    flex: 1;
    flexWrap: wrap;
    flexDirecton: row;
}
.child {
    flexBasis: '50%';
}

回答4:

If you want to make the grid view trully responsive about the device width import Dimesions:

import {
  StyleSheet,
  Text,
  ...
  Dimensions,
} from 'react-native';

And change the gridItem width for this:

gridItem: {
  margin: 5,
  width: Dimensions.get('window').width / 2.2, //Device width divided in almost a half
  height: 150,
  justifyContent: 'center',
  alignItems: 'center',
},

Also you can change the image width to be the same or less as the gridItem.

回答5:

You can use a FlatList and set to it the numColumns={2} prop and style={{ flexDirection: 'column' }}. In my case I'm working with 3 cols: FlatList with numColumns={3}