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

export default class App extends Component {
  constructor() {
    super();
    this.state = {
      counter: 0
    }
  }

  increment = () => {    
    this.setState({ counter: this.state.counter + 1 });
  }
  render() {
    return (
      <View style={styles.container}>
        <Text>Számláló: {this.state.counter}</Text>
        <Button 
          title='Növel'
          onPress={this.increment} 
        />
      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: 'skyblue',
    alignItems: 'center',
    justifyContent: 'center',
  },
});