React Native:无法从其他组件的函数体内部更新组件

// ComponentA.js
import React from 'react';
import { View, Text } from 'react-native';

class ComponentA extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      count: 0,
    };
  }

  updateCount = () => {
    this.setState(prevState => ({
      count: prevState.count + 1,
    }));
  }

  render() {
    return (
      <View>
        <Text>Count: {this.state.count}</Text>
      </View>
    );
  }
}

export default ComponentA;

// ComponentB.js
import React from 'react';
import { Button } from 'react-native';

class ComponentB extends React.Component {
  updateComponentA = () => {
    this.props.updateFunction();
  }

  render() {
    return (
      <Button title="Update ComponentA" onPress={this.updateComponentA} />
    );
  }
}

export default ComponentB;

// App.js
import React from 'react';
import { View } from 'react-native';
import ComponentA from './ComponentA';
import ComponentB from './ComponentB';

class App extends React.Component {
  updateComponentA = () => {
    this.componentARef.updateCount();
  }

  render() {
    return (
      <View>
        <ComponentA ref={ref => { this.componentARef = ref; }} />
        <ComponentB updateFunction={this.updateComponentA} />
      </View>
    );
  }
}

export default App;