title: React try to use a textinput but nothing appears
body: <p>I'm trying to put in place this thing : <a href="https://callstack.github.io/react-native-paper/2.0/text-input.html" rel="nofollow noreferrer">https://callstack.github.io/react-native-paper/2.0/text-input.html</a>
  But it doesn't appear. I have no error but nothing is visible : i got a blank.
  I think this is due to the fact that i don't use a class, but i don't want to use is here.</p>
  <pre><code>import React, { useState } from 'react';
  import { StyleSheet, TextInput, View, Text, Button, Image } from 'react-native';
  import { login } from '../api/mock';
  import EmailForm from '../forms/EmailForm';
  import mainLogo from '../../assets/juliette.jpg';
  
  const LoginScreen = ({ navigation }) =&gt; {
    state = {
      text: ''
    };
    return (
      &lt;View style={styles.main_container}&gt;
          &lt;Image style={styles.image} source={mainLogo} /&gt;
          &lt;TextInput
          label='Email'
          value={this.state.text}
          onChangeText={text =&gt; this.setState({ text })}
          /&gt;
          &lt;EmailForm buttonText=&quot;Se connecter&quot; onSubmit={login} onAuthentication={() =&gt; navigation.navigate('Home')}&gt;
  
          &lt;Button style={styles.button} title=&quot;Créer un compte&quot; onPress={() =&gt; navigation.navigate('CreateAccount')}/&gt;
        &lt;/EmailForm&gt;
      &lt;/View&gt;
    );
  };
  
  
  const styles = StyleSheet.create({
    main_container: {
      flex: 1,
      marginTop: 50,
      justifyContent: 'center',
      marginHorizontal: 16
    },
    textinput: {
      marginLeft: 5,
      marginRight: 5,
      height: 50,
      borderColor: '#000000',
      borderWidth: 1,
      paddingLeft: 5
    },
    image: {
      marginLeft:50,
      height: 300,
      width: 300
    },
    button: {
        flex: 2,
        flexDirection: 'column',
        justifyContent: 'center',
        alignItems: 'center',
        borderBottomWidth: StyleSheet.hairlineWidth
    },
  })
  
  export default LoginScreen;
  </code></pre>
  <p>Thank you for advance</p>