Mobile Development

An app built specifically for one platform using its official language and SDK — Swift/Objective-C for iOS, Kotlin/Java for Android. Native apps have direct access to all platform APIs, best performance, and full platform UI guidelines compliance.

"We're building a native iOS app — using Swift and UIKit gives us the best performance for the real-time drawing feature and full access to the Apple Pencil API."

Development approach that writes one codebase to target multiple platforms (iOS + Android + Web). Frameworks: React Native (JavaScript), Flutter (Dart), Xamarin (C#). Trade-off: faster development, but may have platform-specific gaps or native performance limitations.

"We chose React Native for the cross-platform approach — 85% of the code is shared between iOS and Android, with platform-specific code only for notifications and in-app purchases."

The sequence of states an app passes through: Foreground (active, visible, user interacting), Background (not visible but can execute some tasks), Suspended (in memory but not executing), Killed (removed from memory). Each transition triggers lifecycle callbacks that developers must handle correctly.

"The app crashes on resume because we're not restoring state in onResume — when the app goes to background and back to foreground, we need to refresh the user's session token."

A message sent from a server to a device even when the app is not open. On iOS: delivered via APNs (Apple Push Notification service); on Android: via FCM (Firebase Cloud Messaging). Users must grant permission for notifications. Critical for re-engagement.

"The push notification for order updates requires permission — on iOS we show the permission prompt after the user places their first order, which gives context for why notifications are useful."

A URL that opens a specific screen in a mobile app, bypassing the home screen. Used in notifications, marketing emails, and web-to-app flows. Universal Links (iOS) and App Links (Android) allow the same URL to open the app or fall back to a web page.

"The password reset email contains a deep link that opens the app directly on the password reset screen — users don't have to navigate manually from the home screen."

APK (Android Package) is the distributable file format for Android apps. IPA (iOS App Archive) is the equivalent for iOS. These files are the compiled app ready for installation — uploaded to the Play Store / App Store or distributed for testing via TestFlight or Firebase App Distribution.

"The QA team installs builds directly via APK on Android — they use Firebase App Distribution. For iOS testing, we distribute IPA files through TestFlight after each successful CI build."

The process of signing an app with a cryptographic certificate to verify its origin and ensure it hasn't been tampered with. Required by both Apple and Google. iOS code signing involves certificates, provisioning profiles, and Xcode configuration. Often a source of build-time confusion.

"The iOS build is failing with a code signing error — the provisioning profile has expired. We need to regenerate the profile in Apple Developer and update the certificate in our CI environment."

Apple's official beta testing platform for iOS apps. Allows up to 10,000 external testers to install pre-release builds without going through App Store review. Internal testers (up to 100) get immediate access; external testers need a shorter review.

"We release a TestFlight build every Monday from the main branch — product managers and key beta users test it during the week and give feedback before we submit to the App Store on Friday."

A software tool for running mobile apps on a computer without a physical device. Android Studio uses emulators (which emulate actual Android hardware); Xcode uses simulators (which simulate iOS). Physical device testing is still needed for cameras, GPS, performance, and real-touch input.

"The layout bug only appears on a physical iPhone 14 Pro — the simulator doesn't fully replicate the dynamic island behaviour. Always test on physical devices before submitting to App Store review."

The process Apple uses to approve or reject apps submitted to the App Store. Typically takes 1–3 days. Apps can be rejected for: guideline violations, crashes, misleading metadata, missing privacy policy. Expedited review is available for critical bug fixes.

"Plan for App Store review time in your release schedule — don't push a critical fix to production at 4pm Friday expecting it live by 5pm. It usually takes 24–48 hours, and rejections require a revised resubmit."

Delivering app updates wirelessly to devices without a new App Store/Play Store release. For JavaScript-based apps (React Native with Expo EAS Update), OTA updates can change JS bundles. Native code changes still require a full store release.

"We use OTA updates to push hotfixes for JavaScript bugs in the React Native app — the fix reaches users within hours without waiting for App Store approval."

The automated collection of crash logs from user devices and uploading them to a central dashboard (Sentry, Firebase Crashlytics, Bugsnag). Crash reports include: device model, OS version, app version, stack trace, and breadcrumbs of events leading to the crash.

"After the release, Crashlytics showed a crash rate spike on Android 8 devices — it was a background thread UI update, which is only allowed on Android 8 and earlier. We fixed it in a hotfix within 2 hours."

A transaction made within a mobile app to buy content or features, handled by the platform's payment system (Apple StoreKit, Google Play Billing). Three types: consumable (currency, lives — can buy multiple times), non-consumable (premium feature unlock — buy once), subscription (recurring access).

"All in-app purchases go through StoreKit — we never handle payment card data ourselves. Apple takes a 15–30% commission; the rest goes to us. We must also support restoring purchases for non-consumables."

The portion of the screen guaranteed to be visible and not obscured by system UI elements: rounded corners, the Dynamic Island (iPhone), the home indicator bar (iPhone without home button), or the camera cutout (Android). UI elements must stay within the safe area to be visible.

"The 'Checkout' button is hidden on iPhone 14 Pro because we forgot to respect the safe area — it was positioned at the bottom of the screen under the home indicator bar. We added safeAreaInsets.bottom padding."

Physical vibration used to provide tactile feedback to the user in response to their interaction. On iOS: UIImpactFeedbackGenerator provides different intensities. Used for: button presses, notifications, errors, selections. Should feel natural and purposeful, not gratuitous.

"We added haptic feedback to the 'complete task' button — a soft impact when the user marks a task done. User research showed it made the action feel more satisfying and increased engagement."