text: import React from 'react';
  import { StyleSheet, ScrollView, Text, TextInput, TouchableNativeFeedback, View } from 'react-native';
  
  export default class ChangeAmountScreen extends React.Component {
    static navigationOptions = {
      title: 'Change amount',
    };
  
    constructor(props) {
      super(props);
  
      this.state = { amount: props.amount };    
    };
  
    add = () => {
      const {goBack} = this.props.navigation;
  
      goBack();
    };
  
    render() {
      return (
        <ScrollView
          contentContainerStyle={styles.container}
          style={styles.scroll}
        >
          <Text style={styles.text} >Amount</Text>
          <TextInput
            placeholder="0"
            onChangeText={amount => this.setState( {amount} )}
            keyboardType="numeric"
            underlineColorAndroid="transparent"
            onSubmitEditing={() => this.add()}
          />
  
          <TouchableNativeFeedback
            background={TouchableNativeFeedback.Ripple('#00D900')}
            onPress={() => this.add()}
          >
            <View style={styles.button} >
              <Text style={styles.txtButton} >Change amount</Text>
            </View>
          </TouchableNativeFeedback>
        </ScrollView>
      );
    };  
  };
  
  const styles = StyleSheet.create({
    container: {
      padding: 8,
    },
    scroll: {
      flex: 1,
    },
    button: {
      borderColor: '#00D900',
      borderWidth: 1,
      borderRadius: 5,
      padding: 8,
    },
    txtButton: {
      textAlign: 'center',
      fontSize: 16,
      color: '#003D00',
    },
    text: {
      color: '#003D00',    
    },
  });
  