MyComponent.js

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


class MyComponent extends Component {
    componentWillMount() {
        this.onButtonPress = this.onButtonPress.bind(this);
    }

    onButtonPress() {
        this.doSomething();
    }

    doSomething() {
        console.log('doing something');
    }

    render() {
        return (
            <TouchableOpacity onPress={this.onButtonPress}>
                <View style={{height: 48, width: 96, padding : 10, backgroundColor : 'green'}}>
                    <Text>Press Me</Text>
                </View>
            </TouchableOpacity>
        );
    }    
}