expo-app-design（展会应用程序设计）

Expo App Design

Complete guide for building beautiful apps with Expo Router. Based on official Expo skills from expo/skills repository.

Running the App

CRITICAL: Always try Expo Go first before creating custom builds.

Most Expo apps work in Expo Go without any custom native code. Before running npx expo run:ios or npx expo run:android:

1. Start with Expo Go: Run npx expo start and scan the QR code with Expo Go
2. Check if features work: Test your app thoroughly in Expo Go
3. Only create custom builds when required

When Custom Builds Are Required

You need npx expo run:ios/android or eas build ONLY when using:

• Local Expo modules (custom native code in modules/)
• Apple targets (widgets, app clips, extensions via @bacons/apple-targets)
• Third-party native modules not included in Expo Go
• Custom native configuration that can't be expressed in app.json

Code Style

• Always use kebab-case for file names, e.g. comment-card.tsx
• Always remove old route files when moving or restructuring navigation
• Never use special characters in file names
• Configure tsconfig.json with path aliases, prefer aliases over relative imports
• Be cautious of unterminated strings and escape nested backticks properly

Routes

• Routes belong in the app directory
• Never co-locate components, types, or utilities in the app directory
• Ensure the app always has a route that matches "/"

Library Preferences

Responsiveness

• Always wrap root component in a scroll view for responsiveness
• Use <ScrollView contentInsetAdjustmentBehavior="automatic" /> instead of <SafeAreaView>
• Apply contentInsetAdjustmentBehavior="automatic" to FlatList and SectionList
• Use flexbox instead of Dimensions API
• ALWAYS prefer useWindowDimensions over Dimensions.get()

Styling (Apple HIG)

• Prefer flex gap over margin and padding styles
• Prefer padding over margin where possible
• Inline styles not StyleSheet.create unless reusing styles
• Add entering and exiting animations for state changes
• Use {borderCurve: 'continuous'} for rounded corners unless creating a capsule
• ALWAYS use a navigation stack title instead of custom text element
• Use CSS boxShadow style prop, NEVER use legacy React Native shadow or elevation
• CSS and Tailwind are not supported - use inline styles

// Correct shadow usage
<View style={{ boxShadow: "0 1px 2px rgba(0, 0, 0, 0.05)" }} />

Text Styling

• Add selectable prop to <Text/> displaying important data or error messages
• Counters should use {fontVariant: 'tabular-nums'} for alignment

Navigation

Link

Use <Link href="/path" /> from 'expo-router' for navigation:

import { Link } from 'expo-router';

// Basic link
<Link href="/path" />

// Wrapping custom components
<Link href="/path" asChild>
  <Pressable>...</Pressable>
</Link>

Include <Link.Preview> to follow iOS conventions for context menus and previews:

<Link href="/settings">
  <Link.Trigger>
    <Pressable><Card /></Pressable>
  </Link.Trigger>
  <Link.Preview />
</Link>

Context Menus

<Link href="/settings" asChild>
  <Link.Trigger>
    <Pressable><Card /></Pressable>
  </Link.Trigger>
  <Link.Menu>
    <Link.MenuAction title="Share" icon="square.and.arrow.up" onPress={handleShare} />
    <Link.MenuAction title="Block" icon="nosign" destructive onPress={handleBlock} />
    <Link.Menu title="More" icon="ellipsis">
      <Link.MenuAction title="Copy" icon="doc.on.doc" onPress={() => {}} />
      <Link.MenuAction title="Delete" icon="trash" destructive onPress={() => {}} />
    </Link.Menu>
  </Link.Menu>
</Link>

Modal

<Stack.Screen name="modal" options={{ presentation: "modal" }} />

Sheet

<Stack.Screen
  name="sheet"
  options={{
    presentation: "formSheet",
    sheetGrabberVisible: true,
    sheetAllowedDetents: [0.5, 1.0],
    contentStyle: { backgroundColor: "transparent" }, // Liquid glass on iOS 26+
  }}
/>

Native Tabs (SDK 54+)

Always prefer NativeTabs from 'expo-router/unstable-native-tabs':

import { NativeTabs, Icon, Label, Badge } from "expo-router/unstable-native-tabs";

export default function TabLayout() {
  return (
    <NativeTabs minimizeBehavior="onScrollDown">
      <NativeTabs.Trigger name="index">
        <Label>Home</Label>
        <Icon sf="house.fill" />
        <Badge>9+</Badge>
      </NativeTabs.Trigger>
      <NativeTabs.Trigger name="settings">
        <Icon sf="gear" />
        <Label>Settings</Label>
      </NativeTabs.Trigger>
      <NativeTabs.Trigger name="(search)" role="search">
        <Label>Search</Label>
      </NativeTabs.Trigger>
    </NativeTabs>
  );
}

NativeTabs Rules

• Include a trigger for each tab
• name must match route name exactly (including parentheses)
• Place search tab last to combine with search bar
• Use role prop for common tab types: search, favorites, more, etc.

Icon Component

<Icon sf="house.fill" />                              // SF Symbol only
<Icon sf="house.fill" drawable="ic_home" />           // With Android drawable
<Icon src={require('./icon.png')} />                  // Custom image
<Icon sf={{ default: "house", selected: "house.fill" }} /> // State variants

Badge Component

<Badge>9+</Badge>  // Numeric badge
<Badge />          // Dot indicator

SF Symbols (expo-symbols)

Use SF Symbols for native feel. Never use FontAwesome or Ionicons.

import { SymbolView } from "expo-symbols";
import { PlatformColor } from "react-native";

<SymbolView
  tintColor={PlatformColor("label")}
  resizeMode="scaleAspectFit"
  name="square.and.arrow.down"
  style={{ width: 16, height: 16 }}
/>

Common Icons

Animated Symbols

<SymbolView
  name="checkmark.circle"
  animationSpec={{
    effect: { type: "bounce", direction: "up" }
  }}
/>

Effects: bounce, pulse, variableColor, scale

Symbol Weights

ultraLight, thin, light, regular, medium, semibold, bold, heavy, black

Common Route Structure

app/
  _layout.tsx          — <NativeTabs />
  (index,search)/
    _layout.tsx        — <Stack />
    index.tsx          — Main list
    search.tsx         — Search view

// app/_layout.tsx
import { NativeTabs, Icon, Label } from "expo-router/unstable-native-tabs";

export default function Layout() {
  return (
    <NativeTabs>
      <NativeTabs.Trigger name="(index)">
        <Icon sf="list.dash" />
        <Label>Items</Label>
      </NativeTabs.Trigger>
      <NativeTabs.Trigger name="(search)" role="search" />
    </NativeTabs>
  );
}

// app/(index,search)/_layout.tsx - Shared stack for both tabs
import { Stack } from "expo-router/stack";
import { PlatformColor } from "react-native";

export default function Layout({ segment }) {
  const screen = segment.match(/\((.*)\\)/)?.[1]!;
  const titles = { index: "Items", search: "Search" };

  return (
    <Stack
      screenOptions={{
        headerTransparent: true,
        headerShadowVisible: false,
        headerLargeTitleShadowVisible: false,
        headerLargeStyle: { backgroundColor: "transparent" },
        headerTitleStyle: { color: PlatformColor("label") },
        headerLargeTitle: true,
        headerBlurEffect: "none",
        headerBackButtonDisplayMode: "minimal",
      }}
    >
      <Stack.Screen name={screen} options={{ title: titles[screen] }} />
      <Stack.Screen name="i/[id]" options={{ headerLargeTitle: false }} />
    </Stack>
  );
}

Behavior

• Use expo-haptics conditionally on iOS for delightful experiences
• Use views with built-in haptics like <Switch /> and @react-native-community/datetimepicker
• When a route belongs to a Stack, its first child should be a ScrollView with contentInsetAdjustmentBehavior="automatic"
• Prefer headerSearchBarOptions in Stack.Screen options to add a search bar
• Use <Text selectable /> for data that could be copied
• Format large numbers (1.4M, 38k)
• Never use intrinsic elements like 'img' or 'div' unless in webview or DOM component

Visual Effects

Blur Effects (expo-blur)

import { BlurView } from 'expo-blur';

<BlurView intensity={50} style={StyleSheet.absoluteFill} />

Liquid Glass (expo-glass-effect)

import { GlassView } from 'expo-glass-effect';

<GlassView style={styles.glass} cornerRadius={16} />

Validation Commands

npx tsc --noEmit        # Type check
npx eslint .            # Lint
npm test                # Tests
npx expo-doctor         # Doctor check
npx expo start          # Start dev