React-native:如何在不单击react-native-map中的标记的情况下显示工具提示

import React, { Component } from 'react';
import { View } from 'react-native';
import MapView, { Marker, Callout } from 'react-native-maps';

class MapScreen extends Component {
  render() {
    return (
      <View style={{ flex: 1 }}>
        <MapView
          style={{ flex: 1 }}
          initialRegion={{
            latitude: 37.78825,
            longitude: -122.4324,
            latitudeDelta: 0.0922,
            longitudeDelta: 0.0421,
          }}
        >
          <Marker
            coordinate={{ latitude: 37.78825, longitude: -122.4324 }}
          >
            <Callout>
              {/* 在这里添加工具提示的内容 */}
            </Callout>
          </Marker>
        </MapView>
      </View>
    );
  }
}

export default MapScreen;

<Callout>
  <View>
    <Text>工具提示内容</Text>
  </View>
</Callout>