输入的数据不会在textfield中显示反应原生

Question

用户输入的数据数据不会显示在反应原生材料文本字段中

this.state = {
    userName: ''

}


render() {
    let { userName } = this.state;

    return (

        <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>

            <TextField style={{ color: 'black', marginLeft: windowSize.width / 1.4, color: 'red' }}
                label='Phone number'
                textColor={'red'}
                value={userName}
                labelHeight={40}
                labelPadding={1}
                Bottom padding={8}
                onChangeText={(userName) => this.setState({ userName })}
            />