在本机基本选取器中添加默认选取器项

Question

我在我的expo应用程序中使用本机基础库。我正在绑定api的选项，但问题是我无法添加默认Picker.Item，例如"Please Select".请为我提供一个解决方案。

<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

选取器示例

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