react native add underline to text code example

Example: text input underline react native

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

export default class App extends Component {
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>SEDC</Text>
      <TextInput placeholder="Acct No/User Id" style={styles.textInput} multiline={true}></TextInput>
      <TextInput placeholder="Password" style={styles.textInput}></TextInput>
      <TouchableOpacity style={styles.btn} onPress={this.login}><Text>Log In</Text></TouchableOpacity>
      </View>
    );
  }

  login=()=>{
    alert("testing......");
    // this.props.navigation.navigate('Second');
}
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  },
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  },

  textInput: {
    alignSelf: 'stretch',
    padding: 10,
    marginLeft: 50,
    borderBottomColor:'#000',
    margin:5,
    marginRight:50,
    // backgroundColor: '#000',
},
  btn:{
    alignSelf: 'stretch',
    backgroundColor: '#01c853',
    padding: 10,
    margin:10,
    marginLeft: 100,
    marginRight:100,
    alignItems: 'center',
}
});