在React-Native中，如何为TabBarIOS中的每个NavigatorIOS选项卡调用popToTop()？

import React, { Component } from 'react';
import { TabBarIOS, NavigatorIOS } from 'react-native';

class App extends Component {
  constructor(props) {
    super(props);
    this.navigatorRefs = []; // 用于存储NavigatorIOS组件的引用
  }

  handleTabPress(index) {
    // 在Tab切换时，调用对应NavigatorIOS组件的popToTop()方法
    this.navigatorRefs[index].popToTop();
  }

  render() {
    return (
      <TabBarIOS>
        <TabBarIOS.Item
          title="Tab 1"
          onPress={() => this.handleTabPress(0)}
        >
          <NavigatorIOS
            ref={ref => this.navigatorRefs[0] = ref}
            initialRoute={{
              component: Screen1,
              title: 'Screen 1',
            }}
          />
        </TabBarIOS.Item>
        <TabBarIOS.Item
          title="Tab 2"
          onPress={() => this.handleTabPress(1)}
        >
          <NavigatorIOS
            ref={ref => this.navigatorRefs[1] = ref}
            initialRoute={{
              component: Screen2,
              title: 'Screen 2',
            }}
          />
        </TabBarIOS.Item>
      </TabBarIOS>
    );
  }
}

export default App;