Java connot reduce_Cannot read property 'reduce' of undefined

CrazyCodeBoy老湿，我昨天试了下SectionList，传了个datasouce进去，结果报'Cannot read property 'reduce' of undefined'，我的rn版本是0.43，啥情况呢let food = [

{name: "Lettuce", category: "Vegetable"},

{name: "Apple", category: "Fruit"},

{name: "Orange", category: "Fruit"},

{name: "Potato", category: "Vegetable"}

];

export default class XYRecycle extends Component{

constructor(props){

super(props);

let ds = new ListView.DataSource({

rowHasChanged: (r1, r2) => r1 !== r2,

sectionHeaderHasChanged: (s1, s2) => s1 !== s2

});

this.state={

result:'',

dataSource:ds.cloneWithRowsAndSections(this.convertFoodArrayToMap()),

};

}

convertFoodArrayToMap(){

let foodCategoryMap = {}; // Create the blank map

food.forEach(function(foodItem) {

if (!foodCategoryMap[foodItem.category]) {

// Create an entry in the map for the category if it hasn't yet been created

foodCategoryMap[foodItem.category] = [];

}

foodCategoryMap[foodItem.category].push(foodItem);

});

return foodCategoryMap;

}

render(){

return(

contentContainerStyle={styles.listViewStyle}

renderItem={

({item}) => row

}

renderSectionHeader={

({section}) => section

}

dataSource={this.state.dataSource}

stickySectionHeadersEnabled={false}

/>

)

}

}

然后，

我打了断点也没发现sections属性

求大神指导