Mobile Development Skill

Mobile Development Skill

Use this skill for all Adynato mobile projects built with React Native and Expo.

Stack

• Framework: Expo (managed workflow preferred)
• Navigation: Expo Router (file-based routing)
• Styling: NativeWind (Tailwind for React Native)
• State: Zustand or React Context
• Data Fetching: TanStack Query

API-Driven UI (Critical)

Maximize API-driven content to enable instant updates without App Store review.

App Store review can take 1-7 days. Any UI that can be server-controlled should be, so you can update instantly.

What Should Be API-Driven

What Must Be Native

• Core navigation structure (Expo Router screens)
• Native module integrations
• Performance-critical animations
• Offline-first functionality

Implementation Pattern

// API returns UI configuration
interface HomeConfig {
  sections: Section[]
  featuredBanner?: Banner
  quickActions: QuickAction[]
}

function HomeScreen() {
  const { data: config } = useQuery({
    queryKey: ['home', 'config'],
    queryFn: () => api.get<HomeConfig>('/​api/​home/​config'),
    staleTime: 1000 * 60 * 5, // Cache 5 min
  })

  return (
    <ScrollView>
      {config?.featuredBanner && (
        <Banner data={config.featuredBanner} />
      )}
      {config?.sections.map(section => (
        <DynamicSection key={section.id} config={section} />
      ))}
    </​ScrollView>
  )
}

Feature Flags

// lib/​features.ts
import { useQuery } from '@tanstack/​react-query'

interface FeatureFlags {
  newCheckout: boolean
  darkMode: boolean
  betaFeatures: boolean
}

export function useFeatureFlags() {
  return useQuery({
    queryKey: ['features'],
    queryFn: () => api.get<FeatureFlags>('/​api/​features'),
    staleTime: 1000 * 60 * 15, // 15 min
  })
}

// Usage
function CheckoutButton() {
  const { data: flags } = useFeatureFlags()

  if (flags?.newCheckout) {
    return <NewCheckoutFlow />
  }
  return <LegacyCheckout />
}

Remote Config for Copy

// Fetch all app copy from API
const { data: copy } = useQuery({
  queryKey: ['copy', locale],
  queryFn: () => api.get(`/​api/​copy/​${locale}`),
})

// Use with fallback
<Text>{copy?.welcomeMessage ?? 'Welcome!'}</​Text>

Server-Driven Lists

// API controls what appears and in what order
interface FeedConfig {
  items: FeedItem[]
  layout: 'grid' | 'list'
  columns?: number
}

function Feed() {
  const { data } = useQuery<FeedConfig>({
    queryKey: ['feed'],
    queryFn: () => api.get('/​api/​feed'),
  })

  if (data?.layout === 'grid') {
    return <GridView items={data.items} columns={data.columns} />
  }
  return <ListView items={data.items} />
}

Cache Strategy

Balance freshness with offline support:

const queryClient = new QueryClient({
  defaultOptions: {
    queries: {
      staleTime: 1000 * 60 * 5,    // Fresh for 5 min
      gcTime: 1000 * 60 * 60 * 24, // Keep in cache 24h
    },
  },
})

Project Structure

app/
├── (tabs)/
│   ├── _layout.tsx
│   ├── index.tsx
│   └── profile.tsx
├── (auth)/
│   ├── _layout.tsx
│   ├── login.tsx
│   └── register.tsx
├── _layout.tsx
└── +not-found.tsx
components/
├── ui/
│   ├── Button.tsx
│   └── Input.tsx
└── [feature]/
hooks/
lib/
constants/
assets/
├── images/
└── fonts/

Navigation

Expo Router Patterns

// app/​_layout.tsx - Root layout
import { Stack } from 'expo-router'

export default function RootLayout() {
  return (
    <Stack>
      <Stack.Screen name="(tabs)" options={{ headerShown: false }} />
      <Stack.Screen name="(auth)" options={{ headerShown: false }} />
    </​Stack>
  )
}

// app/(tabs)/​_layout.tsx - Tab navigation
import { Tabs } from 'expo-router'
import { Home, User } from 'lucide-react-native'

export default function TabLayout() {
  return (
    <Tabs>
      <Tabs.Screen
        name="index"
        options={{
          title: 'Home',
          tabBarIcon: ({ color }) => <Home color={color} />,
        }}
      />
      <Tabs.Screen
        name="profile"
        options={{
          title: 'Profile',
          tabBarIcon: ({ color }) => <User color={color} />,
        }}
      />
    </​Tabs>
  )
}

Navigation Actions

import { router } from 'expo-router'

// Navigate
router.push('/​profile')
router.replace('/​home')
router.back()

// With params
router.push({
  pathname: '/​user/[id]',
  params: { id: '123' }
})

Components

Platform-Specific Styles

import { Platform, StyleSheet } from 'react-native'

const styles = StyleSheet.create({
  container: {
    paddingTop: Platform.OS === 'ios' ? 50 : 30,
    ...Platform.select({
      ios: { shadowColor: '#000' },
      android: { elevation: 4 },
    }),
  },
})

Safe Area Handling

import { SafeAreaView } from 'react-native-safe-area-context'

export function Screen({ children }) {
  return (
    <SafeAreaView className="flex-1 bg-white dark:bg-gray-900">
      {children}
    </​SafeAreaView>
  )
}

Pressable Over TouchableOpacity

import { Pressable, Text } from 'react-native'

<Pressable
  onPress={handlePress}
  className="active:opacity-70 bg-blue-500 px-4 py-2 rounded-lg"
>
  <Text className="text-white font-semibold">Press Me</​Text>
</​Pressable>

Images in Mobile

Using Expo Image

Prefer expo-image over React Native's Image:

import { Image } from 'expo-image'

<Image
  source={{ uri: 'https://example.com/​image.webp' }}
  style={{ width: 200, height: 200 }}
  contentFit="cover"
  placeholder={blurhash}
  transition={200}
/>

Local Images

import { Image } from 'expo-image'

<Image
  source={require('@/​assets/​images/​logo.png')}
  style={{ width: 100, height: 100 }}
/>

Native APIs

Permissions Pattern

import * as Location from 'expo-location'

async function requestLocation() {
  const { status } = await Location.requestForegroundPermissionsAsync()

  if (status !== 'granted') {
    // Handle denial gracefully
    return null
  }

  return await Location.getCurrentPositionAsync({})
}

Secure Storage

import * as SecureStore from 'expo-secure-store'

// Store sensitive data
await SecureStore.setItemAsync('token', authToken)

// Retrieve
const token = await SecureStore.getItemAsync('token')

// Delete
await SecureStore.deleteItemAsync('token')

Performance

List Optimization

import { FlashList } from '@shopify/​flash-list'

<FlashList
  data={items}
  renderItem={({ item }) => <ItemCard item={item} />}
  estimatedItemSize={100}
  keyExtractor={(item) => item.id}
/>

Memoization

import { memo, useCallback, useMemo } from 'react'

const ExpensiveComponent = memo(function ExpensiveComponent({ data }) {
  const processed = useMemo(() => processData(data), [data])
  const handlePress = useCallback(() => { ... }, [])

  return <View>...</​View>
})

Testing

Component Testing

import { render, fireEvent } from '@testing-library/​react-native'
import { Button } from '@/​components/​ui/​Button'

test('Button calls onPress', () => {
  const onPress = jest.fn()
  const { getByText } = render(<Button onPress={onPress}>Click</​Button>)

  fireEvent.press(getByText('Click'))
  expect(onPress).toHaveBeenCalled()
})

Build & Deploy

EAS Build

# Development build
eas build --profile development --platform ios

# Production
eas build --profile production --platform all

Environment Variables

// Use expo-constants for env vars
import Constants from 'expo-constants'

const apiUrl = Constants.expoConfig?.extra?.apiUrl

Checklist

Before releasing:

• UI is API-driven where possible (copy, config, feature flags)
• Tested on both iOS and Android
• Safe area handling on all screens
• Keyboard avoiding views where needed
• Loading and error states for all async operations
• Offline handling considered
• Deep linking configured
• App icons and splash screen set
• Performance profiled (no jank)