title: React Native - Button onPress not working
body: <p>I don´t understand why my function is not working when I press the button. No error shows. I also tried onPress={this.loginHandler} and theres a message that says</p>
  
  <blockquote>
    <p>Warning: Failed prop type: The prop onPress is marked as required in Button, but it´s value is undefined.</p>
  </blockquote>
  
  <p>Here's my code:</p>
  
  <pre><code>import React, {Component} from 'react';
  import { Button} from 'react-native';
  
  
  export default class AuthScreen extends Component {
    loginHandler = () =&gt; {
      console.log('P11');
    }
  
  render() {
      return (
        &lt;View&gt;
            &lt;Button style={styles.btnLogin} title='Iniciá sesión' onPress={this.loginHandler}  style={{flex:1}}/&gt;
        &lt;/View&gt;
      );
    }
  }
  </code></pre>