<Content>
  <Grid style={{flexWrap: 'wrap', flex: 1}}>
    {this.state.stories.map(function(story, index){
        if (index % 2 === 0) {
            return <Col key={ index } style={{margin: 5, width: Dimensions.get('window').width / 2.2}}>
                    <View>
                        <Image style={{ height: 250, borderRadius: 10}} source={{uri: story.picture_url}} />
                    </View>
                </Col>
        } else{
            return <Col key={ index } style={{margin: 5, width: Dimensions.get('window').width / 2.2}}>
                <View style={{marginTop: 25}}>
                    <Image style={{height: 250, borderRadius: 10}} source={{uri: story.picture_url}} />
                </View>
            </Col>
            }
        }.bind(this))
    }
  </Grid>
</Content>

/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 * @flow
 */

import React, { Component } from 'react';
import {
  AppRegistry,
  StyleSheet,
  Text,
  View
} from 'react-native';

export default class layout extends Component {
  render() {
    return (
      <View style={styles.container}>
        <View style={styles.column}>
          <View style={[styles.box, {backgroundColor:'red'}]}/>
          <View style={[styles.box, {backgroundColor:'pink'}]}/>
          <View style={[styles.box, {backgroundColor:'orange'}]}/>
        </View>
        <View style={styles.space_between_columns}/>
        <View style={styles.column}>
          <View style={[styles.box, {backgroundColor:'blue'}]}/>
          <View style={[styles.box, {backgroundColor:'green'}]}/>
          <View style={[styles.box, {backgroundColor:'purple'}]}/>
        </View>
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    flexDirection:'row',
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  column: {
    flexDirection:'column',
    justifyContent:'space-between',
    alignItems:'center',
    height:200,
    width:50
  },
  space_between_columns:{
    width:100
  },
  box: {
    height:50,
    width:50
  }
});

AppRegistry.registerComponent('layout', () => layout);

<Content>
<Grid style={{flexWrap: 'wrap', flex: 1}}>
{this.state.stories.map(function(story, index){
    if (index % 2 === 0) {
        return
    <Row style={{flex:1}}>
    <Col key={ index } style={{margin: 5, flex:.5}}>
                <View>
                    <Image style={{ height: 250, borderRadius: 10}} source={{uri: story.picture_url}} />
                </View>
            </Col>
            {(() => { if (index + 1 < (this.state.subjects.length - 1)) {
            return <Col key={ index + 1 } style={{margin: 5, flex:.5}}>
                <View style={{marginTop: 25}}>
                    <Image style={{height: 250, borderRadius: 10}} source={{uri: this.state.stories[index+1].picture_url}} />
                </View>
                   </Col>
        }
        else
        {
            return <Col style={{margin: 5, flex:.5}}/>
        }
             })()}

    }

    }.bind(this))
}