在本机基本选择器中添加默认选择器项目

Question

我正在博览会应用程序中使用本机基本库。我正在绑定api中的选项，但是问题是我无法添加默认的Picker.Item，例如"Please Select"。请为我提供解决方案。

<Picker
  mode="dropdown"
  selectedValue={this.state.selected}
  style={styles.inputPicker}
  onValueChange={this.onValueChange.bind(this)}>
  {this.courtsArray.map((item) => {
     return (<Picker.Item label={item.Name} value={item.CountryCode} key={item.ID}/>);
  })}
</Picker>

Answer 1

[Picker的示例

import React, {Component} from 'react';
import {View, Text, Picker, TouchableOpacity} from 'react-native';

export default class Pickers extends Component {

  state = {user: ''};
  updateUser = user => {
    this.setState({user: user});
  };

  render() {
    return (
      <View>
        <Text style={{fontSize: 25, margin: 8, color: 'black'}}>
          Picker Select
        </Text>
        <View style={{margin: 10, elevation: 1, borderWidth: 1}}>
          <Picker
            selectedValue={this.state.user}
            pickerStyleType="Android"
            onValueChange={this.updateUser}
            mode="dialog">
            <Picker.Item label="React Native" value="React Native" />
            <Picker.Item label="Android Studio" value="Android Studio" />
            <Picker.Item label="Swift" value="Swift" />
          </Picker>
        </View>
        <Text
          style={{
            alignSelf: 'center',
            fontSize: 20,
            fontWeight: 'bold',
            color: 'red',
          }}>
          {this.state.user}
        </Text>
      </View>
    );
  }
}

祝你好运