render() {
        return (
            <View>
                <FlatList
                    numColumns={2}
                    style={ styles.cardContainer }
                    keyExtractor={ this._keyExtractor }
                    data={ this.state.itemList }
                    renderItem={ this._renderItem }
                    >
                </FlatList>
            </View>
        );
    }

cardContainer: {
    flex: 1,
    flexDirection: 'column'
},

card: {
    flex: 1,
    margin: 10,
    flexBasis: '50%'
},