Set up export button to export a simple file

components/home.js

@@ -68,6 +68,12 @@ export default class Home extends Component {
               title="Go to chart">
             </Button>
           </View>
+          <View style={styles.homeButton}>
+            <Button
+              onPress={() => navigate('settings')}
+              title="Go to settings">
+            </Button>
+          </View>
           <View style={styles.homeButton}>
             <Button
               onPress={() => fillWithDummyData()}

components/settings.js

@@ -0,0 +1,66 @@
+import React, { Component } from 'react'
+import {
+  View,
+  Button,
+  Text,
+  ScrollView,
+  Picker
+} from 'react-native'
+import Share from 'react-native-share'
+import { Base64 } from 'js-base64'
+import styles from '../styles/index'
+
+export default class Settings extends Component {
+  constructor(props) {
+    super(props)
+
+    this.state = {
+      pickerVisible: false
+    }
+  }
+
+  render() {
+    return (
+      <ScrollView>
+        <Text style={styles.welcome}>{this.state.welcomeText}</Text>
+        <View style={styles.homeButtons}>
+          <View style={styles.homeButton}>
+            <Button
+              onPress={() => this.setState({pickerVisible: true})}
+              title="Edit symptoms for today">
+            </Button>
+          </View>
+        </View>
+        {this.state.pickerVisible &&
+          <Picker
+            selectedValue='json'
+            style={{ height: 50, width: 200 }}
+            onValueChange={ async format => {
+              const data = makeDataURI(format)
+              console.log(data)
+              try {
+                await Share.open({
+                  title: 'My Drip data export',
+                  url: data,
+                  subject: 'My Drip data export',
+                  type: 'text/csv',
+                  showAppsToView: true
+                })
+              } catch (err) {
+                console.log(err)
+              }
+            }}>
+            <Picker.Item label="JSON" value="json" />
+            <Picker.Item label="CSV" value="csv" />
+          </Picker>
+        }
+      </ScrollView>
+    )
+  }
+}
+
+function makeDataURI(format) {
+  const data = {hello: "world"}
+  const encoded = Base64.encodeURI(JSON.stringify(data))
+  return `data:text/csv;base64,${encoded}`
+}