React Native Academy · レッスン

ヘッダー付きSectionList

SectionListで項目をセクションにまとめ、各グループに固定表示されるセクションヘッダーを描画し、項目間のセパレーターをカスタマイズします

「ヘッダー付きSectionList」はCoddyKit上の無料React Native Academyレッスンです。これはレッスン3/4です。下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。これはReact Native Academy学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 React Native Academyコースには全4レッスンが含まれています。

このレッスンの一部はまだ翻訳されておらず、英語で表示されています。

When to Use SectionList

SectionList is the React Native component for displaying grouped lists — data divided into sections, each with its own header. It is ideal for contacts lists sorted alphabetically, settings screens with grouped options, or e-commerce categories. Like FlatList, it virtualizes rendering for performance.

SectionList Data Format

SectionList expects its sections prop to be an array of section objects. Each section object must have a data array containing the items for that section. You also typically include a title or other metadata to render the section header.

const SECTIONS = [
  {
    title: 'A',
    data: [
      { id: '1', name: 'Alice' },
      { id: '2', name: 'Andrew' },
    ],
  },
  {
    title: 'B',
    data: [
      { id: '3', name: 'Bob' },
      { id: '4', name: 'Beth' },
    ],
  },
];

Rendering Items with renderItem

The renderItem function in SectionList receives an object with the current item, its index within the section, and the section object itself. This gives you access to both the item data and the enclosing section's metadata in the same render call.

const renderItem = ({ item, section }) => (
  <View style={styles.row}>
    <Text>{item.name}</Text>
    <Text style={styles.sectionLabel}>{section.title}</Text>
  </View>
);

Rendering Section Headers

Pass a renderSectionHeader function to display a header above each section. The function receives { section } — the current section object. Returning a View with a colored background makes the header stand out from the items below it.

const renderSectionHeader = ({ section }) => (
  <View style={styles.sectionHeader}>
    <Text style={styles.sectionTitle}>{section.title}</Text>
  </View>
);

<SectionList
  sections={SECTIONS}
  renderItem={renderItem}
  renderSectionHeader={renderSectionHeader}
  keyExtractor={(item) => item.id}
/>

Sticky Section Headers

By default, section headers scroll with the list. Set stickySectionHeadersEnabled to true to make headers stick to the top of the screen as you scroll past them — the same behavior you see in the iOS Contacts app. This is set to true by default on iOS and false on Android.

<SectionList
  sections={SECTIONS}
  renderItem={renderItem}
  renderSectionHeader={renderSectionHeader}
  keyExtractor={(item) => item.id}
  stickySectionHeadersEnabled={true}
/>

Section Footer with renderSectionFooter

Use renderSectionFooter to render content after the last item in each section. This is useful for showing a 'View all' link or a count of remaining items below a truncated group. The function receives the same { section } argument as renderSectionHeader.

const renderSectionFooter = ({ section }) => (
  <TouchableOpacity>
    <Text style={styles.viewAll}>
      View all {section.data.length} {section.title} contacts
    </Text>
  </TouchableOpacity>
);

Item Separators in SectionList

Like FlatList, SectionList supports ItemSeparatorComponent to render dividers between items within a section. SectionList also provides SectionSeparatorComponent to render a separator between the end of one section (or its footer) and the start of the next section's header.

const ItemSeparator = () => <View style={styles.separator} />;
const SectionSeparator = () => <View style={styles.sectionSeparator} />;

<SectionList
  sections={SECTIONS}
  renderItem={renderItem}
  renderSectionHeader={renderSectionHeader}
  keyExtractor={(item) => item.id}
  ItemSeparatorComponent={ItemSeparator}
  SectionSeparatorComponent={SectionSeparator}
/>

A Full SectionList Example

Bringing it all together: define your sections data, provide renderItem and renderSectionHeader, set a keyExtractor, and optionally enable sticky headers. This pattern covers the majority of grouped list use cases in production apps.

import { SectionList, View, Text, StyleSheet } from 'react-native';

export default function ContactsScreen() {
  return (
    <SectionList
      sections={SECTIONS}
      keyExtractor={(item) => item.id}
      renderItem={({ item }) => (
        <View style={styles.row}><Text>{item.name}</Text></View>
      )}
      renderSectionHeader={({ section }) => (
        <View style={styles.header}><Text style={styles.headerText}>{section.title}</Text></View>
      )}
      stickySectionHeadersEnabled
    />
  );
}

Building Data for SectionList from a Flat Array

Often your API returns a flat array. You need to group items by a common property before passing them to SectionList. Use Array.reduce to build a map, then convert it to the sections format. Sort the sections alphabetically for a predictable order.

function groupByFirstLetter(contacts) {
  const map = contacts.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],
  }));
}

Scrolling to a Specific Section

Use a ref on the SectionList and call scrollToLocation to jump to a specific item or section header. This is essential for alphabetic index bars (like the sidebar in iOS Contacts) where tapping a letter scrolls the list to that section.

const sectionListRef = useRef(null);

const scrollToSection = (sectionIndex) => {
  sectionListRef.current?.scrollToLocation({
    sectionIndex,
    itemIndex: 0,
    animated: true,
  });
};

<SectionList ref={sectionListRef} sections={SECTIONS} ... />

Performance Tips for SectionList

The same performance rules that apply to FlatList apply to SectionList. Stabilize renderItem and renderSectionHeader with useCallback. Avoid creating new objects inline in the sections prop on every render — memoize the processed sections data with useMemo.

const sections = useMemo(
  () => groupByFirstLetter(contacts),
  [contacts]
);

const renderItem = useCallback(({ item }) => (
  <Row item={item} />
), []);

Quick Check

Test your understanding of SectionList with headers from this lesson.

Lesson Recap

In this lesson you learned: SectionList sections prop takes an array of objects each with a data array, renderSectionHeader renders a title above each group, and stickySectionHeadersEnabled pins headers to the top as users scroll. Next up we build a complete Contacts List App combining SectionList, search, and pull-to-refresh.

よくある質問

「ヘッダー付きSectionList」レッスンは無料ですか？

はい。「ヘッダー付きSectionList」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、React Native Academyコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 React Native Academyコースには全4レッスンが含まれています。

「ヘッダー付きSectionList」で何を学びますか？

SectionListで項目をセクションにまとめ、各グループに固定表示されるセクションヘッダーを描画し、項目間のセパレーターをカスタマイズしますブラウザで直接実行するハンズオンコードでReact Native Academyを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。

React Native Academyを始めるのに経験は必要ですか？

事前経験は必要ありません。CoddyKitのReact Native Academyは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。これはレッスン3/4です。

「ヘッダー付きSectionList」レッスンにはどのくらい時間がかかりますか？

ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。

このReact Native Academyレッスンでコードを書いて実行できますか？

はい。すべてのReact Native Academyレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。

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