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


export default class App extends React.Component
{
    constructor(props)
    {
        super(props);
        this.state = {text1: 'initial'};
    }

    setVal ()
    {
        this.setState (st => {st.text1 = new Date ().toString ()});
        //this.forceUpdate ();
    }

    render()
    {
        return (
            <View style={{ alignItems: 'center', justifyContent: 'center', flex: 1}}>
            <Text style={{fontSize: 30, margin: 40}}>text1 is {this.state.text1}</Text>


            <Button
                onPress={
                            () => {console.log("text1=" + this.state.text1);
                        }}
                title="log data"
                color="green"
            />

            <Button
                onPress={this.setVal.bind (this)}
                title="change data"
                color="orange"
            />


           <TextInput
                style={{height: 40, width: 200, margin: 30, borderColor: 'grey', borderWidth: 2}}
                onChangeText={str => this.setState({text1: str})}
                value={this.state.text1}
            />
      </View>
    );
  }
}

this.setState({ text1: new Date().toString() });