Easy everything in Mobile Dev
Rosetta ends for Intel-only Mac apps at macOS 27 as Apple sets a hard deadline
Apple is winding down Rosetta, the translation layer that let Intel-only Mac apps run on Apple silicon since 2020. From macOS 26.4, users launching non-native apps may see an update notification, and macOS 27 is the last release that runs them at all, except older unmaintained games.
Managing Per-Environment Configuration in React Native
Use per-environment env files plus build flavors or schemes, inject at build time, keep secrets off the device.
iOS Provisioning Profiles and Signing Certificates
The certificate proves developer identity, the App ID names the app, the profile binds certificate, App ID, and devices.
Unit testing vs component testing in React Native
Unit tests verify isolated functions/logic with Jest; component tests render components and assert behavior with React Native Testing Library.
What are the three pillars of the New Architecture?
JSI for direct JS-native calls, Fabric as the new renderer, and TurboModules for lazy native modules, all unified by CodeGen for type-safe bindings.
How do you send a one-off event from native to JS?
Emit an event from native using an event emitter and subscribe in JS with NativeEventEmitter, or resolve a promise/callback for a single result.
Cost of console.log and production-safe debugging
Each console.log serializes data and, when devtools are attached, crosses the bridge synchronously, blocking the JS thread; strip logs in release and use Flipper, dev tools, or remote crash and analytics tools.
FlatList and list virtualization
Use FlatList (or SectionList) which virtualizes, rendering only items near the viewport and recycling as you scroll, unlike ScrollView which mounts everything.
The JS thread and why it bottlenecks performance
A single thread runs your JS, React reconciliation, and event handling; blocking it delays updates and gestures, and it is separate from the UI thread.
Getting a one-time GPS location
Ensure permission, then call a getCurrentPosition wrapped in a promise (or Expo Location.getCurrentPositionAsync) with await inside try/catch, reading coords.latitude and longitude.
Requesting runtime permissions on iOS and Android
Declare permissions in Info.plist and AndroidManifest, then check status and request at runtime just before use, handling granted, denied, and blocked.
Persisting key-value preferences across launches
AsyncStorage for simple non-sensitive key-value, MMKV for speed, SecureStore or Keychain for secrets.
Build a mount fade-in with Animated API
Create an Animated.Value(0) in a ref, drive it with Animated.timing inside useEffect, bind it to opacity on Animated.View.
useNativeDriver in the Animated API
Native driver runs animations on the UI thread so they stay smooth even if JS is busy, but only supports non-layout props like transform and opacity.
Cross-platform shadow with Platform API
IOS uses shadowColor/Offset/Opacity/Radius, Android uses elevation; merge both via Platform.select inside a style.
Platform-specific file extensions
Name files Component.ios.js and Component.android.js; import without the extension and the bundler picks the right one per platform.
Axios advantages over fetch
Axios auto-parses JSON, rejects on HTTP error status, and offers interceptors, timeouts, and cancellation out of the box.
Local state versus global state management
Keep state local with useState/useReducer when it is used by one component or its subtree; reach for Redux or Zustand when many distant components share and mutate the same state.
Prop drilling and the Context API
Prop drilling is threading props through many intermediate components that do not use them; Context provides a value to a subtree so consumers read it directly.
SectionList versus FlatList for grouped data
FlatList takes a flat data array; SectionList takes a sections array of objects each with a data array and optional title, and supports renderSectionHeader and sticky headers.
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