Building a Contacts List App
Combine SectionList, alphabetic section headers, a search filter, and pull-to-refresh to build a realistic contacts screen with smooth scroll performance.
Building a Contacts List App is a free React Native Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the React Native Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
App Overview: Contacts List
In this lesson you will build a realistic contacts list screen that combines everything from the FlatList and SectionList lessons. The app will display contacts grouped alphabetically, support a search filter, allow pull-to-refresh, and maintain smooth performance even with hundreds of entries.
Defining the Contacts Data
Start with a static array of contact objects. In a real app this would come from the device's contacts API or a remote server. Each contact has an id, name, and phone. A unique numeric or string ID is essential for the keyExtractor.
const CONTACTS = [
{ id: '1', name: 'Alice Brown', phone: '+1-555-0101' },
{ id: '2', name: 'Andrew Chen', phone: '+1-555-0102' },
{ id: '3', name: 'Bob Davis', phone: '+1-555-0201' },
{ id: '4', name: 'Carol Evans', phone: '+1-555-0301' },
// ... more contacts
];Search Filter State
Add a searchQuery state variable and filter the contacts array before grouping. The filter converts both the query and contact name to lowercase for a case-insensitive match. Wrap the filtering and grouping in useMemo so it only recomputes when the contacts or query changes.
const [searchQuery, setSearchQuery] = useState('');
const filteredContacts = useMemo(() => {
if (!searchQuery) return CONTACTS;
return CONTACTS.filter((c) =>
c.name.toLowerCase().includes(searchQuery.toLowerCase())
);
}, [searchQuery]);Grouping Contacts Alphabetically
Convert the filtered flat array into the SectionList sections format. Reduce the contacts into a map keyed by the first letter, then sort the keys and map them to section objects. This transformation runs inside useMemo alongside the filter for a single computed value.
const sections = useMemo(() => {
const map = filteredContacts.reduce((acc, contact) => {
const letter = contact.name[0].toUpperCase();
if (!acc[letter]) acc[letter] = [];
acc[letter].push(contact);
return acc;
}, {});
return Object.keys(map).sort().map((key) => ({
title: key,
data: map[key],
}));
}, [filteredContacts]);Search Bar Component
Render a TextInput above the SectionList as the ListHeaderComponent so it scrolls with the list. Bind it to searchQuery state with onChangeText. Use the clearButtonMode prop on iOS to show a native clear button inside the input.
const SearchBar = () => (
<TextInput
style={styles.searchBar}
placeholder='Search contacts...'
value={searchQuery}
onChangeText={setSearchQuery}
clearButtonMode='while-editing'
/>
);Contact Row Component
Build a memoized row component using React.memo to prevent unnecessary re-renders. The row shows the contact's initials in a colored avatar circle and their name and phone number on the right. Memoizing the row component is critical for smooth scrolling with hundreds of contacts.
const ContactRow = React.memo(({ item }) => (
<View style={styles.row}>
<View style={styles.avatar}>
<Text style={styles.initials}>{item.name[0]}</Text>
</View>
<View>
<Text style={styles.name}>{item.name}</Text>
<Text style={styles.phone}>{item.phone}</Text>
</View>
</View>
));Section Header Component
The alphabetic section header is a simple View with the letter. Give it a distinct background color and sticky behavior so it stays visible as the user scrolls through each letter group. Keep the component small and memoized since it renders once per letter.
const SectionHeader = ({ section }) => (
<View style={styles.sectionHeader}>
<Text style={styles.sectionTitle}>{section.title}</Text>
</View>
);Pull-to-Refresh Integration
Simulate refreshing by introducing a refreshing state. On refresh, clear the search query (so users see all contacts again), wait briefly to simulate a network call, then set refreshing to false. In a real app you would re-fetch from the device contacts API or the server.
const [refreshing, setRefreshing] = useState(false);
const onRefresh = () => {
setRefreshing(true);
setSearchQuery('');
setTimeout(() => setRefreshing(false), 1000);
};Empty State When No Results
When the filtered sections array is empty (no contacts match the search), display an informative empty state using ListEmptyComponent. Tell the user no contacts match their query and suggest they clear the search. This is far better than showing a blank screen.
const ListEmpty = () => (
<View style={styles.empty}>
<Text>No contacts found for '{searchQuery}'</Text>
<Button title='Clear Search' onPress={() => setSearchQuery('')} />
</View>
);Assembling the Full Screen
Combine all the pieces: SectionList with the sections data, memoized renderItem, renderSectionHeader, keyExtractor, sticky headers, pull-to-refresh, and ListHeaderComponent for the search bar. The result is a production-quality contacts screen.
export default function ContactsScreen() {
return (
<SectionList
sections={sections}
keyExtractor={(item) => item.id}
renderItem={({ item }) => <ContactRow item={item} />}
renderSectionHeader={({ section }) => <SectionHeader section={section} />}
stickySectionHeadersEnabled
refreshing={refreshing}
onRefresh={onRefresh}
ListHeaderComponent={SearchBar}
ListEmptyComponent={ListEmpty}
/>
);
}Navigating to a Contact Detail Screen
Make each row tappable by wrapping the ContactRow in a TouchableOpacity that calls navigation.navigate('ContactDetail', { contactId: item.id }). The detail screen reads the ID from route.params and fetches the full contact data, following the React Navigation pattern you learned earlier.
const ContactRow = React.memo(({ item, onPress }) => (
<TouchableOpacity onPress={() => onPress(item)} style={styles.row}>
<View style={styles.avatar}>
<Text style={styles.initials}>{item.name[0]}</Text>
</View>
<View>
<Text style={styles.name}>{item.name}</Text>
<Text style={styles.phone}>{item.phone}</Text>
</View>
</TouchableOpacity>
));Quick Check
Test your understanding of the Contacts List App architecture from this lesson.
Lesson Recap
In this lesson you learned: combine SectionList, search filtering, and useMemo for an efficient contacts screen, memoize row components with React.memo to maintain scroll performance, and integrate pull-to-refresh and empty states for a polished UX. Next up we dive into the useRef hook and mutable values.
Frequently asked questions
Is the “Building a Contacts List App” lesson free?
Yes — the full text of “Building a Contacts List App” is free to read here on the web, and the React Native Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the React Native Academy course, upgrade to CoddyKit PRO.
What will I learn in “Building a Contacts List App”?
Combine SectionList, alphabetic section headers, a search filter, and pull-to-refresh to build a realistic contacts screen with smooth scroll performance. You practise React Native Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start React Native Academy?
No prior experience is required. React Native Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Building a Contacts List App” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this React Native Academy lesson?
Yes. Every React Native Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- FlatList Data, renderItem, and keyExtractor
- Pull-to-Refresh and Load More
- SectionList with Headers
- Building a Contacts List App