Flutter Dev

Flutter Development Guide

A practical guide for building cross-platform applications with Flutter 3 and Dart. Focuses on proven patterns, state management, and performance optimization.

Quick Reference

Widget Patterns

Purpose	Component
State management (simple)	StateProvider + ConsumerWidget
State management (complex)	NotifierProvider / Bloc
Async data	FutureProvider / AsyncNotifierProvider
Real-time streams	StreamProvider
Navigation	GoRouter + context.go/push
Responsive layout	LayoutBuilder + breakpoints
List display	ListView.builder
Complex scrolling	CustomScrollView + Slivers
Hooks	HookWidget + useState/useEffect
Forms	Form + TextFormField + validation

Performance Patterns

Purpose	Solution
Prevent rebuilds	const constructors
Selective updates	ref.watch(provider.select(...))
Isolate repaints	RepaintBoundary
Lazy lists	ListView.builder
Heavy computation	compute() isolate
Image caching	cached_network_image

Core Principles

Widget Optimization

• Use const constructors wherever possible
• Extract static widgets to separate const classes
• Use Key for list items (ValueKey, ObjectKey)
• Prefer ConsumerWidget over StatefulWidget for state

State Management

• Riverpod for dependency injection and simple state
• Bloc/Cubit for event-driven workflows and complex logic
• Never mutate state directly (create new instances)
• Use select() to minimize rebuilds

Layout

• 8pt spacing increments (8, 16, 24, 32, 48)
• Responsive breakpoints: mobile (<650), tablet (650-1100), desktop (>1100)
• Support all screen sizes with flexible layouts
• Follow Material 3 / Cupertino design guidelines

Performance

• Profile with DevTools before optimizing
• Target <16ms frame time for 60fps
• Use RepaintBoundary for complex animations
• Offload heavy work with compute()

Checklist

Widget Best Practices

• const constructors on all static widgets
• Proper Key on list items
• ConsumerWidget for state-dependent widgets
• No widget building inside build() method
• Extract reusable widgets to separate files

State Management

• Immutable state objects
• select() for granular rebuilds
• Proper provider scoping
• Dispose controllers and subscriptions
• Handle loading/error states

Navigation

• GoRouter with typed routes
• Auth guards via redirect
• Deep linking support
• State preservation across routes

Performance

• Profile mode testing (flutter run --profile)
• <16ms frame rendering time
• No unnecessary rebuilds (DevTools check)
• Images cached and resized
• Heavy computation in isolates

Testing

• Widget tests for UI components
• Unit tests for business logic
• Integration tests for user flows
• Bloc tests with blocTest()

References

Topic	Reference
Widget patterns, const optimization, responsive layout	Widget Patterns
Riverpod providers, notifiers, async state	Riverpod State Management
Bloc, Cubit, event-driven state	Bloc State Management
GoRouter setup, routes, deep linking	GoRouter Navigation
Feature-based structure, dependencies	Project Structure
Profiling, const optimization, DevTools	Performance Optimization
Widget tests, integration tests, mocking	Testing Strategies
iOS/Android/Web specific implementations	Platform Integration
Implicit/explicit animations, Hero, transitions	Animations
Dio, interceptors, error handling, caching	Networking
Form validation, FormField, input formatters	Forms
i18n, flutter_localizations, intl	Localization

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Flutter, Dart, Material Design, and Cupertino are trademarks of Google LLC and Apple Inc. respectively. Riverpod, Bloc, and GoRouter are open-source packages by their respective maintainers.