So I have a Button component

import React, { Component } from 'react';

import { View, Text, TouchableNativeFeedback } from 'react-native';



class Button extends Component {

    generateComponent() {

        const { buttonStyle, textStyle } = this.styles;

        const { text } = this.props;



        switch (this.props.platform) {

            case 'android':

                return (

                    <TouchableNativeFeedback onPress={this.props.onPress}>

                        <View style={buttonStyle}>

                            <Text style={textStyle}>{text}</Text>

                        </View>

                    </TouchableNativeFeedback>

                );

            case 'ios':

                return 0;

        }

    }



    render() {

        return (

            <View>

                { this.generateComponent() }

            </View>

        );

    }



    styles = {

        buttonStyle: {

            borderRadius: 100,

            justifyContent: 'center',

            height: parseInt(this.props.size, 10),

            width: parseInt(this.props.size, 10),

            backgroundColor: this.props.color,

            elevation: 3

        },

        textStyle: {

            fontWeight: 'bold',

            fontSize: parseInt(this.props.fontSize, 10),

            lineHeight: parseInt(this.props.fontSize, 10)

                + Math.floor(parseInt(this.props.fontSize, 10) / 10) + 1,

            color: this.props.fontColor,

            textAlign: 'center'

        }

    }

}



Button.propTypes = {

    text: React.PropTypes.string.isRequired,

    platform: React.PropTypes.string.isRequired,

    size: React.PropTypes.string.isRequired,

    color: React.PropTypes.string.isRequired,

    fontColor: React.PropTypes.string.isRequired,

    fontSize: React.PropTypes.string.isRequired,

    onPress: React.PropTypes.function.isRequired

};



export default Button;

And I call this component in the component Home

import React, { Component } from 'react';

import { View } from 'react-native';

import Metas from '../components/Metas';

import Button from '../components/Button';



export default class Home extends Component {

    constructor(props) {

        super(props);

        this.state = { metas: ['Meta 1', 'Meta 2', 'Meta 3'] };

    }



    render() {

        return (

            <View>

                <Metas data={ this.state.metas } />

                <Button

                    text=+

                    platform={ this.props.platform }

                    onPress={ this._handleButtonPress }

                    size='50'

                    fontSize='25'

                    color='#FFD600'

                    fontColor='white'

                />

            </View>

        );

    }



    _handleButtonPress() {

        console.log(Hello!);

    }

}



Home.propTypes = {

    platform: React.PropTypes.string.isRequired

};

The problem is that if I include the PropTypes I get an error saying that the onPress prop is undefined.

I do not understand why I recieve this error. I consoled logged the typeof onPress and it prints function.

Any suggestion??