Sefism Mobile Development Cheat Sheet

What it is

The Mobile development cheat sheet is the quick-revision companion to Sefism's Mobile development roadmap, covering everything from your platform's language to shipping in the stores. Read a chapter top to bottom to refresh a stage, or jump to a single concept for its definition, a short snippet and the classic mistake.

Mobile has more platform-specific detail than most areas, and the sheet is built around that: the ideas (state, offline-first, permissions, release tracks) are shared, while the names, APIs and snippets follow your platform.

Four editions

• Flutter: Flutter and Dart 3, from widgets to shipping on Google Play and the App Store. 66 concepts.
• React Native: React Native with Expo and TypeScript, from components to shipping in both stores. 68 concepts.
• Android: Kotlin 2 and Jetpack Compose, from composables to shipping on Google Play. 66 concepts.
• iOS: Swift 6 and SwiftUI, from views to shipping on the App Store. 65 concepts.

Each edition has seven chapters: a language chapter of its own, then six shared chapters with entries specific to your platform mixed in.

Chapter by chapter

1. Language essentials

• Dart essentials: sound null safety, var, final and const, immutable models, sealed classes, records and patterns, collections, Futures, Streams, isolates and pubspec.yaml.
• JavaScript and TypeScript essentials: types, interfaces and unions, optional chaining and nullish coalescing, immutable updates, closures and stale values, promises, discriminated unions and npm.
• Kotlin essentials: null safety, lambdas and extensions, data and sealed classes, collections, coroutines, dispatchers, Flow and StateFlow, and Gradle version catalogs.
• Swift essentials: optionals, structs against classes, enums with associated values, closures and capture lists, protocols, throwing errors, async/await, actors, MainActor and Sendable, and Swift Package Manager.

2. UI and layout

Declarative UI, rows, columns and stacks, lazy lists, text input and forms, theming and dark mode, platform design guidelines, safe areas and screen sizes, and hot reload and previews. Platform entries include Flutter's "constraints go down, sizes go up" and BuildContext, React Native's core components with Flexbox and StyleSheet, Compose modifiers and recomposition, and SwiftUI view modifiers.

3. State and navigation

Local UI state, unidirectional data flow, shared app state, view models, stack navigation, tabs, sheets and dialogs, passing data between screens and deep links, with ChangeNotifier for Flutter, the rules of hooks for React Native, configuration changes and process death for Android, and @Binding and property wrappers for iOS.

4. Networking and local data

Calling a REST API and parsing JSON, loading, error and empty states, a local database, key-value storage, secure storage for tokens, the repository pattern, offline-first, access and refresh tokens, and timeouts with backoff. React Native adds TanStack Query; iOS adds Codable and JSONDecoder.

5. Device features and notifications

The app lifecycle, runtime permissions, photo picker and camera, location, local and push notifications, and background work and OS limits. Android adds foreground services, Flutter adds plugins and platform channels, and React Native adds the New Architecture and Expo Go against development builds.

6. Testing, performance and accessibility

Unit, UI and end-to-end tests, fakes and dependency injection, profiling and dropped frames, startup time and app size, screen reader labels, text scaling and a mobile security review, with re-renders and list performance for React Native and baseline profiles for Android.

7. Publishing and releases

The largest chapter: app IDs, versions and build numbers, release builds for your platform (Flutter builds, EAS Build and Submit, R8, or archiving and uploading in Xcode), Android signing and Play App Signing, iOS certificates and provisioning, Google Play testing tracks, TestFlight, privacy declarations, store review, crash reporting and rollouts.

Chapters link to library resources for depth, such as Material Design 3, Apple's Human Interface Guidelines, OWASP Mobile Application Security, Play Console Help and the App Review Guidelines.

Rules of thumb worth remembering

Seven rules apply to every platform, and each edition adds its own. The shared ones include:

• Profile and judge performance on a release build running on a mid-range phone, never a debug build on a flagship.
• Ask for a permission at the moment a feature needs it, with one sentence saying why, and keep the app usable if the answer is no.
• Keep one source of truth for each piece of data: screens read from the local store and the network only refreshes it.
• Never ship secrets in the app bundle, because anything inside an APK or IPA can be extracted.
• Switch on airplane mode in the middle of a request to see how every screen handles a lost connection.
• Before each release, complete your main flow with TalkBack or VoiceOver on and at the largest text size.

Platform tips cover things such as backing up your Android upload key somewhere other than your laptop, adding packages with npx expo install, and starting async work from SwiftUI's .task modifier. A 149-term glossary sits at the back.

How to use it with the roadmap

• After each stage: the seven chapters follow the roadmap's seven stages. Read the chapter and check every pitfall line.
• While building: keep the networking chapter open when you build offline sync, and the device features chapter open when you add permissions.
• On release day: the publishing chapter doubles as a checklist, from version numbers to privacy declarations and testing tracks.
• Before a technical conversation: the state, networking and testing chapters are the ones to reread: be ready to explain where state lives, how the app behaves offline and how you tested it.

How it works on Sefism

Everything here is free to learn from. The public page lists every chapter title, with the first chapters open to read. Keeping the sheet uses credits, and new members get starting credits when they join. Adding the Mobile development roadmap to your dashboard (your first roadmap is free) opens this sheet with it. In the member area you can switch between the four editions.

Related on Sefism

• How to choose between frontend, backend, mobile, cloud, security, data and AI
• The UI/UX design cheat sheet for layout, accessibility and design systems from the design side
• The Frontend development cheat sheet if you are coming to React Native from the web
• Flutter Documentation and Expo Documentation

FAQ

Is this enough to learn Flutter (or Swift, or Kotlin)? No. It is a revision sheet; the roadmap and its official documentation picks do the teaching.

Which versions does it cover? Dart 3 for Flutter, Expo with TypeScript for React Native, Kotlin 2 with Jetpack Compose for Android, and Swift 6 with SwiftUI for iOS.

Does the Flutter edition cover both stores? Yes. The Flutter and React Native editions include both Google Play and App Store publishing entries.