在react-native中如何获取选择标签值或索引

constructor(props) {
  super(props);
  this.state = {
    selectedValue: '', // 初始化选择标签的值
    selectedIndex: -1, // 初始化选择标签的索引
  };
}

import { Picker } from 'react-native';

// ...

<Picker
  selectedValue={this.state.selectedValue}
  onValueChange={(itemValue, itemIndex) => {
    this.setState({
      selectedValue: itemValue,
      selectedIndex: itemIndex,
    });
  }}
>
  <Picker.Item label="Option 1" value="option1" />
  <Picker.Item label="Option 2" value="option2" />
  <Picker.Item label="Option 3" value="option3" />
</Picker>

handleButtonClick() {
  const selectedValue = this.state.selectedValue;
  const selectedIndex = this.state.selectedIndex;
  console.log('Selected value:', selectedValue);
  console.log('Selected index:', selectedIndex);
}