Filtrar datos de un Json

Audiolibros.js

'use strict';
import React, {Component} from 'react';
import {View, Image, StyleSheet, Text, FlatList, TouchableHighlight, ScrollView} from 'react-native';
import { Icon, Button, Container, Header, Content, Left } from 'native-base'

import AudiosData from '../../data/AudiosData.json';
import MostrarAudios from './MostrarAudios'

export default class Audiolibros extends Component {

  constructor(props) {
    super (props)

    this.state = {
      TemaId: this.props.navigation.state.params.TemaId,
    }

  }

  _renderSeparator = () => {
    return (
        <View style={styles.flatseparator} />
    )
  }



  _renderItem(item) {
    
    return (
      <TouchableHighlight style = { styles.flatview } onPress = { () => { navigate('MostrarAudios', {AudiosData}); } }>
        <View style={{ flex: 1, justifyContent: 'center' }}>
              
          if( {item.idcat} === {this.state.TemaId} ){
            <Text>{item.nombrelibro}</Text>
          }

        </View>
      </TouchableHighlight>    )
  }

  render() {
    return (

    <Container>
      <Content>

        <FlatList
          data={AudiosData.Audiolibros}
          keyExtractor={(item) => item.idlibro }
          renderItem={({item}) => this._renderItem(item)}
          ItemSeparatorComponent={this._renderSeparator}/>

      </Content>
    </Container>);
  }
}