Update data automatically in react-native app

export default class App extends React.Component {

  constructor(props){
    super(props);
    this.state ={ 
      isLoading: true,
      _dataSource:[],
    }
  }

  componentDidMount(){
    return fetch('url minha api')
      .then((response) => response.json())
      .then((responseJson) => {

        this.setState({
          isLoading: false,
          _dataSource: responseJson.minhasinformacoes,
          get dataSource() {
            return this._dataSource;
          },
          set dataSource(value) {
            this._dataSource = value;
          },
        }, function(){

        });

      })
      .catch((error) =>{
        console.error(error);
      });
  }



  render(){

    setTimeout(() => {
      this.setState({
        _dataSource: this.state._dataSource + _dataSource
      })
    }, 1000);
    

    if(this.state.isLoading){
      return(
        <View style={{flex: 1, padding: 20}}>
          <ActivityIndicator/>
        </View>
      )
    }

    return(
      <View style={{flex: 1, paddingTop:20}}>
        /*Quando houvesse mudanças atualizasse os campos ProductName e 
          CategoryName atuamaticamente*/
        <FlatList
          data={this.state._dataSource}
          renderItem={({item}) => <Text>{item.ProductName}, {item.CategoryName} </Text>}
          keyExtractor={({id}, index) => id}
        />
      </View>
    );
  }
}