Tutorial Flutter: Budowanie Aplikacji Wieloplatformowej dla Poczatkujacych

Flutter rewolucjonizuje tworzenie aplikacji mobilnych, umozliwiajac budowanie aplikacji na iOS i Android z jednej bazy kodu. Ten framework opracowany przez Google laczy natywna wydajnosc z wyjatkowa produktywnoscia dzieki silnikowi renderujacemu Skia i deklaratywnemu systemowi widgetow. Niniejszy przewodnik obejmuje budowe kompletnej aplikacji, od instalacji po dobre praktyki produkcyjne.

Flutter 3.27 - Styczen 2026

Flutter 3.27 przynosi znaczace ulepszenia: natywna obsluga Material 3 domyslnie, nowe zoptymalizowane animacje Impeller oraz integracja z Dart 3.6 z eksperymentalnymi makrami. Framework kompiluje teraz do natywnego ARM64 dla optymalnej wydajnosci.

Konfiguracja srodowiska

Konfiguracja Fluttera wymaga kilku krokow. Flutter SDK zawiera wszystko, co potrzebne: framework, narzedzia do budowania i menedzer pakietow Dart.

bash

# terminal
# Download Flutter SDK (macOS/Linux)
git clone https://github.com/flutter/flutter.git -b stable
export PATH="$PATH:`pwd`/flutter/bin"

# Verify installation and dependencies
flutter doctor

# Create a new project
flutter create --org com.example my_app
cd my_app

# Run in development mode
flutter run

Polecenie flutter doctor weryfikuje, czy wszystkie zaleznosci sa zainstalowane: Android Studio, Xcode (macOS) i skonfigurowane emulatory.

yaml

# pubspec.yaml
name: my_app
description: Cross-platform Flutter application
publish_to: 'none'
version: 1.0.0+1

environment:
  sdk: '>=3.6.0 <4.0.0'

dependencies:
  flutter:
    sdk: flutter
  # UI and design
  cupertino_icons: ^1.0.8
  google_fonts: ^6.2.1
  # State management
  flutter_riverpod: ^2.6.1
  # Navigation
  go_router: ^14.6.2
  # HTTP and API
  dio: ^5.7.0
  # Local storage
  shared_preferences: ^2.3.4

dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_lints: ^5.0.0

flutter:
  uses-material-design: true

Ten plik pubspec.yaml konfiguruje podstawowe zaleznosci dla nowoczesnej aplikacji Flutter.

Architektura projektu Flutter

Przejrzysta struktura projektu ulatwia utrzymanie i rozwoj aplikacji. Ta organizacja wyraznie rozdziela odpowiedzialnosci.

text

lib/
├── main.dart                 # Entry point
├── app.dart                  # App configuration
├── core/
│   ├── constants/           # Colors, dimensions, strings
│   ├── theme/               # Material 3 theme
│   └── utils/               # Utility functions
├── features/
│   ├── auth/                # Authentication feature
│   │   ├── data/           # Repositories, data sources
│   │   ├── domain/         # Models, use cases
│   │   └── presentation/   # Screens, widgets, providers
│   └── home/               # Home feature
│       ├── data/
│       ├── domain/
│       └── presentation/
├── shared/
│   ├── widgets/            # Reusable widgets
│   └── providers/          # Shared providers
└── routing/
    └── app_router.dart     # Route configuration

Architektura "feature-first" grupuje caly kod zwiazany z dana funkcjonalnoscia w tym samym katalogu, co ulatwia nawigacje i refaktoryzacje.

Architektura Feature-First

Podejscie feature-first organizuje kod wedlug funkcjonalnosci biznesowej zamiast typu technicznego. Kazda funkcjonalnosc zawiera wlasne modele, widgety i logike, co czyni kod bardziej modularnym i testowalnym.

Zrozumienie widgetow Flutter

Widgety sa podstawowymi elementami budulcowymi Fluttera. Wszystko jest widgetem: przyciski, tekst, layouty, a nawet sama aplikacja. Flutter udostepnia dwa rodzaje widgetow: StatelessWidget (bez stanu) i StatefulWidget (ze stanem lokalnym).

lib/shared/widgets/custom_button.dartdart

import 'package:flutter/material.dart';

/// Custom reusable button widget throughout the application.
/// Automatically handles loading and disabled states.
class CustomButton extends StatelessWidget {
  // Required and optional widget parameters
  final String label;
  final VoidCallback? onPressed;
  final bool isLoading;
  final bool isOutlined;

  // Constructor with named parameters for clarity
  const CustomButton({
    super.key,
    required this.label,
    this.onPressed,
    this.isLoading = false,
    this.isOutlined = false,
  });

  @override
  Widget build(BuildContext context) {
    // Access theme for consistent styles
    final theme = Theme.of(context);

    // Conditional build based on button type
    if (isOutlined) {
      return OutlinedButton(
        // Disable button during loading
        onPressed: isLoading ? null : onPressed,
        style: OutlinedButton.styleFrom(
          padding: const EdgeInsets.symmetric(
            horizontal: 24,
            vertical: 16,
          ),
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
        ),
        child: _buildChild(theme),
      );
    }

    return FilledButton(
      onPressed: isLoading ? null : onPressed,
      style: FilledButton.styleFrom(
        padding: const EdgeInsets.symmetric(
          horizontal: 24,
          vertical: 16,
        ),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(12),
        ),
      ),
      child: _buildChild(theme),
    );
  }

  /// Builds button content with loading state handling.
  Widget _buildChild(ThemeData theme) {
    if (isLoading) {
      return const SizedBox(
        height: 20,
        width: 20,
        child: CircularProgressIndicator(
          strokeWidth: 2,
          color: Colors.white,
        ),
      );
    }
    return Text(label);
  }
}

Ten widget enkapsuluje logike wyswietlania przyciskow z automatyczna obsluga stanu ladowania.

lib/shared/widgets/user_card.dartdart

import 'package:flutter/material.dart';
import '../../features/auth/domain/models/user.dart';

/// Card displaying user information.
/// Uses Material 3 with consistent elevation and shape.
class UserCard extends StatelessWidget {
  final User user;
  final VoidCallback? onTap;

  const UserCard({
    super.key,
    required this.user,
    this.onTap,
  });

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    // Material 3 Card with InkWell for ripple effect
    return Card(
      // Adaptive elevation based on theme
      elevation: 2,
      // Consistent rounded shape
      shape: RoundedRectangleBorder(
        borderRadius: BorderRadius.circular(16),
      ),
      // Clipping so ripple respects borders
      clipBehavior: Clip.antiAlias,
      child: InkWell(
        onTap: onTap,
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Row(
            children: [
              // Avatar with image or initials
              CircleAvatar(
                radius: 28,
                backgroundImage: user.avatarUrl != null
                    ? NetworkImage(user.avatarUrl!)
                    : null,
                child: user.avatarUrl == null
                    ? Text(user.initials)
                    : null,
              ),
              const SizedBox(width: 16),
              // User information
              Expanded(
                child: Column(
                  crossAxisAlignment: CrossAxisAlignment.start,
                  children: [
                    Text(
                      user.displayName,
                      style: theme.textTheme.titleMedium?.copyWith(
                        fontWeight: FontWeight.w600,
                      ),
                    ),
                    const SizedBox(height: 4),
                    Text(
                      user.email,
                      style: theme.textTheme.bodyMedium?.copyWith(
                        color: theme.colorScheme.onSurfaceVariant,
                      ),
                    ),
                  ],
                ),
              ),
              // Navigation icon
              Icon(
                Icons.chevron_right,
                color: theme.colorScheme.onSurfaceVariant,
              ),
            ],
          ),
        ),
      ),
    );
  }
}

Kompozycja widgetow pozwala budowac zlozone interfejsy z prostych, wielokrotnego uzytku blokow.

Zarzadzanie stanem z Riverpod

Riverpod stanowi nowoczesne rozwiazanie do zarzadzania stanem w Flutterze. Ta biblioteka oferuje deklaratywne, typowane i testowalne podejscie do wspoldzielenia stanu miedzy widgetami.

lib/features/auth/domain/models/user.dartdart

/// Immutable user model with fromJson factory.
class User {
  final String id;
  final String email;
  final String displayName;
  final String? avatarUrl;
  final DateTime createdAt;

  const User({
    required this.id,
    required this.email,
    required this.displayName,
    this.avatarUrl,
    required this.createdAt,
  });

  /// Generates initials from display name.
  String get initials {
    final parts = displayName.split(' ');
    if (parts.length >= 2) {
      return '${parts[0][0]}${parts[1][0]}'.toUpperCase();
    }
    return displayName.substring(0, 2).toUpperCase();
  }

  /// Creates instance from JSON (API response).
  factory User.fromJson(Map<String, dynamic> json) {
    return User(
      id: json['id'] as String,
      email: json['email'] as String,
      displayName: json['display_name'] as String,
      avatarUrl: json['avatar_url'] as String?,
      createdAt: DateTime.parse(json['created_at'] as String),
    );
  }

  /// Converts to JSON for API submission.
  Map<String, dynamic> toJson() {
    return {
      'id': id,
      'email': email,
      'display_name': displayName,
      'avatar_url': avatarUrl,
      'created_at': createdAt.toIso8601String(),
    };
  }
}

lib/features/auth/presentation/providers/auth_provider.dartdart

import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../../data/repositories/auth_repository.dart';
import '../../domain/models/user.dart';

/// Authentication state representing different possible cases.
sealed class AuthState {
  const AuthState();
}

class AuthInitial extends AuthState {
  const AuthInitial();
}

class AuthLoading extends AuthState {
  const AuthLoading();
}

class AuthAuthenticated extends AuthState {
  final User user;
  const AuthAuthenticated(this.user);
}

class AuthUnauthenticated extends AuthState {
  const AuthUnauthenticated();
}

class AuthError extends AuthState {
  final String message;
  const AuthError(this.message);
}

/// Provider for authentication repository.
final authRepositoryProvider = Provider<AuthRepository>((ref) {
  return AuthRepository();
});

/// Main provider managing authentication state.
final authProvider = StateNotifierProvider<AuthNotifier, AuthState>((ref) {
  final repository = ref.watch(authRepositoryProvider);
  return AuthNotifier(repository);
});

/// Notifier handling authentication logic.
class AuthNotifier extends StateNotifier<AuthState> {
  final AuthRepository _repository;

  AuthNotifier(this._repository) : super(const AuthInitial()) {
    // Check initial state on startup
    checkAuthStatus();
  }

  /// Checks if a user is already logged in.
  Future<void> checkAuthStatus() async {
    state = const AuthLoading();
    try {
      final user = await _repository.getCurrentUser();
      if (user != null) {
        state = AuthAuthenticated(user);
      } else {
        state = const AuthUnauthenticated();
      }
    } catch (e) {
      state = const AuthUnauthenticated();
    }
  }

  /// Signs in user with email and password.
  Future<void> signIn(String email, String password) async {
    state = const AuthLoading();
    try {
      final user = await _repository.signIn(email, password);
      state = AuthAuthenticated(user);
    } catch (e) {
      state = AuthError(e.toString());
    }
  }

  /// Creates a new user account.
  Future<void> signUp(String email, String password, String displayName) async {
    state = const AuthLoading();
    try {
      final user = await _repository.signUp(email, password, displayName);
      state = AuthAuthenticated(user);
    } catch (e) {
      state = AuthError(e.toString());
    }
  }

  /// Signs out the user.
  Future<void> signOut() async {
    state = const AuthLoading();
    await _repository.signOut();
    state = const AuthUnauthenticated();
  }
}

Wzorzec klas zamknietych (Dart 3.0+) zapewnia, ze wszystkie przypadki stanu sa obslugiwane przy uzyciu wyrazen switch.

Gotowy na rozmowy o Flutter?

Ćwicz z naszymi interaktywnymi symulatorami, flashcards i testami technicznymi.

Odkryj Flutter

Nawigacja z GoRouter

GoRouter upraszcza deklaratywna nawigacje we Flutterze. Ta biblioteka zarzadza trasami, parametrami, przekierowaniami i zagniezdzona nawigacja.

lib/routing/app_router.dartdart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import '../features/auth/presentation/providers/auth_provider.dart';
import '../features/auth/presentation/screens/login_screen.dart';
import '../features/auth/presentation/screens/register_screen.dart';
import '../features/home/presentation/screens/home_screen.dart';
import '../features/home/presentation/screens/profile_screen.dart';
import '../shared/widgets/shell_scaffold.dart';

/// Provider for router with authentication handling.
final routerProvider = Provider<GoRouter>((ref) {
  // Listen to authentication state changes
  final authState = ref.watch(authProvider);

  return GoRouter(
    // Initial route
    initialLocation: '/',
    // Refresh router when auth changes
    refreshListenable: GoRouterRefreshStream(ref, authProvider),
    // Handle redirects based on authentication
    redirect: (context, state) {
      final isAuthenticated = authState is AuthAuthenticated;
      final isAuthRoute = state.matchedLocation.startsWith('/auth');

      // Not authenticated on protected route → login
      if (!isAuthenticated && !isAuthRoute) {
        return '/auth/login';
      }

      // Authenticated on auth route → home
      if (isAuthenticated && isAuthRoute) {
        return '/';
      }

      return null; // No redirect
    },
    routes: [
      // Auth routes (without shell)
      GoRoute(
        path: '/auth/login',
        name: 'login',
        builder: (context, state) => const LoginScreen(),
      ),
      GoRoute(
        path: '/auth/register',
        name: 'register',
        builder: (context, state) => const RegisterScreen(),
      ),
      // Protected routes with shell (bottom navigation)
      ShellRoute(
        builder: (context, state, child) {
          return ShellScaffold(child: child);
        },
        routes: [
          GoRoute(
            path: '/',
            name: 'home',
            builder: (context, state) => const HomeScreen(),
          ),
          GoRoute(
            path: '/profile',
            name: 'profile',
            builder: (context, state) => const ProfileScreen(),
          ),
          GoRoute(
            path: '/profile/:userId',
            name: 'userProfile',
            builder: (context, state) {
              // Extract route parameter
              final userId = state.pathParameters['userId']!;
              return ProfileScreen(userId: userId);
            },
          ),
        ],
      ),
    ],
    // Custom error page
    errorBuilder: (context, state) => Scaffold(
      body: Center(
        child: Text('Page not found: ${state.error}'),
      ),
    ),
  );
});

/// Stream to trigger router refresh.
class GoRouterRefreshStream extends ChangeNotifier {
  GoRouterRefreshStream(Ref ref, StateNotifierProvider provider) {
    ref.listen(provider, (previous, next) {
      notifyListeners();
    });
  }
}

Automatyczne przekierowanie na podstawie stanu uwierzytelniania zapewnia, ze chronione trasy pozostaja niedostepne dla nieuwierzytelnionych uzytkownikow.

lib/shared/widgets/shell_scaffold.dartdart

import 'package:flutter/material.dart';
import 'package:go_router/go_router.dart';

/// Scaffold with bottom navigation bar for protected routes.
class ShellScaffold extends StatelessWidget {
  final Widget child;

  const ShellScaffold({
    super.key,
    required this.child,
  });

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: child,
      bottomNavigationBar: NavigationBar(
        // Determine active index based on route
        selectedIndex: _calculateSelectedIndex(context),
        onDestinationSelected: (index) => _onItemTapped(index, context),
        destinations: const [
          NavigationDestination(
            icon: Icon(Icons.home_outlined),
            selectedIcon: Icon(Icons.home),
            label: 'Home',
          ),
          NavigationDestination(
            icon: Icon(Icons.person_outline),
            selectedIcon: Icon(Icons.person),
            label: 'Profile',
          ),
        ],
      ),
    );
  }

  /// Calculates navigation index based on current route.
  int _calculateSelectedIndex(BuildContext context) {
    final location = GoRouterState.of(context).matchedLocation;
    if (location.startsWith('/profile')) return 1;
    return 0;
  }

  /// Navigates to route corresponding to index.
  void _onItemTapped(int index, BuildContext context) {
    switch (index) {
      case 0:
        context.goNamed('home');
      case 1:
        context.goNamed('profile');
    }
  }
}

Material 3 NavigationBar automatycznie dostosowuje sie do jasnych i ciemnych motywow.

Ekrany i formularze

Tworzenie interaktywnych ekranow laczy widgety, zarzadzanie stanem i walidacje formularzy.

lib/features/auth/presentation/screens/login_screen.dartdart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import '../providers/auth_provider.dart';
import '../../../../shared/widgets/custom_button.dart';

/// Login screen with validated form.
class LoginScreen extends ConsumerStatefulWidget {
  const LoginScreen({super.key});

  @override
  ConsumerState<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends ConsumerState<LoginScreen> {
  // Global key for the form
  final _formKey = GlobalKey<FormState>();
  // Controllers for text fields
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  // Local state for password visibility
  bool _obscurePassword = true;

  @override
  void dispose() {
    // Resource cleanup
    _emailController.dispose();
    _passwordController.dispose();
    super.dispose();
  }

  /// Submits the login form.
  Future<void> _submit() async {
    // Validate all fields
    if (_formKey.currentState!.validate()) {
      await ref.read(authProvider.notifier).signIn(
            _emailController.text.trim(),
            _passwordController.text,
          );
    }
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final authState = ref.watch(authProvider);
    final isLoading = authState is AuthLoading;

    // Listen for errors to display snackbar
    ref.listen<AuthState>(authProvider, (previous, next) {
      if (next is AuthError) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text(next.message),
            backgroundColor: theme.colorScheme.error,
          ),
        );
      }
    });

    return Scaffold(
      body: SafeArea(
        child: Center(
          child: SingleChildScrollView(
            padding: const EdgeInsets.all(24),
            child: Form(
              key: _formKey,
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  // Logo or title
                  Icon(
                    Icons.flutter_dash,
                    size: 80,
                    color: theme.colorScheme.primary,
                  ),
                  const SizedBox(height: 16),
                  Text(
                    'Sign In',
                    style: theme.textTheme.headlineMedium?.copyWith(
                      fontWeight: FontWeight.bold,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 32),
                  // Email field with validation
                  TextFormField(
                    controller: _emailController,
                    keyboardType: TextInputType.emailAddress,
                    textInputAction: TextInputAction.next,
                    decoration: const InputDecoration(
                      labelText: 'Email',
                      hintText: 'example@email.com',
                      prefixIcon: Icon(Icons.email_outlined),
                    ),
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return 'Email is required';
                      }
                      // Basic email format validation
                      if (!RegExp(r'^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$')
                          .hasMatch(value)) {
                        return 'Invalid email format';
                      }
                      return null;
                    },
                  ),
                  const SizedBox(height: 16),
                  // Password field with visibility toggle
                  TextFormField(
                    controller: _passwordController,
                    obscureText: _obscurePassword,
                    textInputAction: TextInputAction.done,
                    onFieldSubmitted: (_) => _submit(),
                    decoration: InputDecoration(
                      labelText: 'Password',
                      prefixIcon: const Icon(Icons.lock_outlined),
                      suffixIcon: IconButton(
                        icon: Icon(
                          _obscurePassword
                              ? Icons.visibility_outlined
                              : Icons.visibility_off_outlined,
                        ),
                        onPressed: () {
                          setState(() {
                            _obscurePassword = !_obscurePassword;
                          });
                        },
                      ),
                    ),
                    validator: (value) {
                      if (value == null || value.isEmpty) {
                        return 'Password is required';
                      }
                      if (value.length < 8) {
                        return 'Minimum 8 characters';
                      }
                      return null;
                    },
                  ),
                  const SizedBox(height: 24),
                  // Sign in button
                  CustomButton(
                    label: 'Sign In',
                    isLoading: isLoading,
                    onPressed: _submit,
                  ),
                  const SizedBox(height: 16),
                  // Link to registration
                  TextButton(
                    onPressed: () => context.goNamed('register'),
                    child: const Text('No account? Create one'),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}

Uzycie ConsumerStatefulWidget laczy stan lokalny (kontrolery formularzy) ze stanem globalnym (Riverpod).

Zarzadzanie kontrolerami

Instancje TextEditingController musza byc zwalniane w metodzie dispose(), aby uniknac wyciekow pamieci. Ta regula dotyczy wszystkich kontrolerow i listenerow tworzonych recznie.

Komunikacja HTTP z Dio

Dio zapewnia potezne API HTTP z interceptorami, obsluga bledow i automatyczna transformacja odpowiedzi.

lib/core/network/api_client.dartdart

import 'package:dio/dio.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import '../constants/api_constants.dart';

/// Provider for Dio HTTP client.
final apiClientProvider = Provider<ApiClient>((ref) {
  return ApiClient();
});

/// HTTP client configured with interceptors.
class ApiClient {
  late final Dio _dio;

  ApiClient() {
    _dio = Dio(
      BaseOptions(
        baseUrl: ApiConstants.baseUrl,
        connectTimeout: const Duration(seconds: 10),
        receiveTimeout: const Duration(seconds: 10),
        headers: {
          'Content-Type': 'application/json',
          'Accept': 'application/json',
        },
      ),
    );

    // Add interceptors
    _dio.interceptors.addAll([
      _AuthInterceptor(),
      _LoggingInterceptor(),
    ]);
  }

  /// Generic GET request.
  Future<T> get<T>(
    String path, {
    Map<String, dynamic>? queryParameters,
    T Function(dynamic)? fromJson,
  }) async {
    try {
      final response = await _dio.get(
        path,
        queryParameters: queryParameters,
      );
      if (fromJson != null) {
        return fromJson(response.data);
      }
      return response.data as T;
    } on DioException catch (e) {
      throw _handleError(e);
    }
  }

  /// Generic POST request.
  Future<T> post<T>(
    String path, {
    dynamic data,
    T Function(dynamic)? fromJson,
  }) async {
    try {
      final response = await _dio.post(path, data: data);
      if (fromJson != null) {
        return fromJson(response.data);
      }
      return response.data as T;
    } on DioException catch (e) {
      throw _handleError(e);
    }
  }

  /// Sets the authentication token.
  void setAuthToken(String token) {
    _dio.options.headers['Authorization'] = 'Bearer $token';
  }

  /// Clears the authentication token.
  void clearAuthToken() {
    _dio.options.headers.remove('Authorization');
  }

  /// Converts Dio errors to readable exceptions.
  Exception _handleError(DioException error) {
    switch (error.type) {
      case DioExceptionType.connectionTimeout:
      case DioExceptionType.sendTimeout:
      case DioExceptionType.receiveTimeout:
        return Exception('Connection timeout. Check your connection.');
      case DioExceptionType.badResponse:
        final statusCode = error.response?.statusCode;
        final message = error.response?.data['message'] ?? 'Server error';
        return Exception('Error $statusCode: $message');
      case DioExceptionType.cancel:
        return Exception('Request cancelled');
      default:
        return Exception('Network error: ${error.message}');
    }
  }
}

/// Interceptor to automatically add token.
class _AuthInterceptor extends Interceptor {
  @override
  void onRequest(
    RequestOptions options,
    RequestInterceptorHandler handler,
  ) {
    // Token is added via setAuthToken()
    handler.next(options);
  }

  @override
  void onError(
    DioException err,
    ErrorInterceptorHandler handler,
  ) {
    // Handle 401 for token refresh
    if (err.response?.statusCode == 401) {
      // TODO: Implement token refresh
    }
    handler.next(err);
  }
}

/// Logging interceptor for development.
class _LoggingInterceptor extends Interceptor {
  @override
  void onRequest(
    RequestOptions options,
    RequestInterceptorHandler handler,
  ) {
    print('→ ${options.method} ${options.path}');
    handler.next(options);
  }

  @override
  void onResponse(
    Response response,
    ResponseInterceptorHandler handler,
  ) {
    print('← ${response.statusCode} ${response.requestOptions.path}');
    handler.next(response);
  }

  @override
  void onError(
    DioException err,
    ErrorInterceptorHandler handler,
  ) {
    print('✗ ${err.response?.statusCode} ${err.requestOptions.path}');
    handler.next(err);
  }
}

Interceptory centralizuja logike uwierzytelniania i logowania bez zanieczyszczania kazdego zapytania.

Niestandardowy motyw z Material 3

Spojny motyw gwarantuje jednolite doswiadczenie uzytkownika. Material 3 (Material You) dostosowuje sie do preferencji systemowych.

lib/core/theme/app_theme.dartdart

import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';

/// Application theme configuration.
class AppTheme {
  // Brand primary color
  static const _primaryColor = Color(0xFF6750A4);

  /// Material 3 light theme.
  static ThemeData get lightTheme {
    // Generate color scheme from primary color
    final colorScheme = ColorScheme.fromSeed(
      seedColor: _primaryColor,
      brightness: Brightness.light,
    );

    return ThemeData(
      useMaterial3: true,
      colorScheme: colorScheme,
      // Custom typography
      textTheme: GoogleFonts.interTextTheme(),
      // AppBar configuration
      appBarTheme: AppBarTheme(
        centerTitle: true,
        elevation: 0,
        backgroundColor: colorScheme.surface,
        foregroundColor: colorScheme.onSurface,
      ),
      // Form field configuration
      inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: colorScheme.surfaceContainerHighest.withOpacity(0.5),
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide.none,
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(color: colorScheme.primary, width: 2),
        ),
        errorBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(color: colorScheme.error),
        ),
        contentPadding: const EdgeInsets.symmetric(
          horizontal: 16,
          vertical: 16,
        ),
      ),
      // Button configuration
      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
        ),
      ),
      outlinedButtonTheme: OutlinedButtonThemeData(
        style: OutlinedButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
        ),
      ),
      // Card configuration
      cardTheme: CardTheme(
        elevation: 2,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(16),
        ),
      ),
    );
  }

  /// Material 3 dark theme.
  static ThemeData get darkTheme {
    final colorScheme = ColorScheme.fromSeed(
      seedColor: _primaryColor,
      brightness: Brightness.dark,
    );

    return ThemeData(
      useMaterial3: true,
      colorScheme: colorScheme,
      textTheme: GoogleFonts.interTextTheme(
        ThemeData.dark().textTheme,
      ),
      appBarTheme: AppBarTheme(
        centerTitle: true,
        elevation: 0,
        backgroundColor: colorScheme.surface,
        foregroundColor: colorScheme.onSurface,
      ),
      inputDecorationTheme: InputDecorationTheme(
        filled: true,
        fillColor: colorScheme.surfaceContainerHighest.withOpacity(0.5),
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide.none,
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(color: colorScheme.primary, width: 2),
        ),
        errorBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(color: colorScheme.error),
        ),
        contentPadding: const EdgeInsets.symmetric(
          horizontal: 16,
          vertical: 16,
        ),
      ),
      filledButtonTheme: FilledButtonThemeData(
        style: FilledButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
        ),
      ),
      outlinedButtonTheme: OutlinedButtonThemeData(
        style: OutlinedButton.styleFrom(
          minimumSize: const Size(double.infinity, 52),
          shape: RoundedRectangleBorder(
            borderRadius: BorderRadius.circular(12),
          ),
        ),
      ),
      cardTheme: CardTheme(
        elevation: 2,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(16),
        ),
      ),
    );
  }
}

ColorScheme.fromSeed automatycznie generuje kompletna i dostepna palete kolorow z jednego koloru.

Konfiguracja aplikacji

Punkt wejscia aplikacji inicjalizuje Riverpod i konfiguruje motywy.

lib/main.dartdart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'app.dart';

void main() {
  // Ensure Flutter bindings are initialized
  WidgetsFlutterBinding.ensureInitialized();

  // Launch application with Riverpod scope
  runApp(
    const ProviderScope(
      child: App(),
    ),
  );
}

lib/app.dartdart

import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'core/theme/app_theme.dart';
import 'routing/app_router.dart';

/// Root application widget.
class App extends ConsumerWidget {
  const App({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    // Get configured router
    final router = ref.watch(routerProvider);

    return MaterialApp.router(
      title: 'My Flutter App',
      debugShowCheckedModeBanner: false,
      // Theme configuration
      theme: AppTheme.lightTheme,
      darkTheme: AppTheme.darkTheme,
      themeMode: ThemeMode.system,
      // Router configuration
      routerConfig: router,
    );
  }
}

ThemeMode.system automatycznie dostosowuje motyw do preferencji uzytkownika.

Podsumowanie

Flutter zapewnia kompletny ekosystem do budowania wydajnych aplikacji wieloplatformowych. Polaczenie deklaratywnych widgetow, Riverpod do zarzadzania stanem i GoRouter do nawigacji pozwala budowac aplikacje latwe w utrzymaniu i skalowalne.

Lista kontrolna na start z Flutterem

✅ Zainstalowac Flutter SDK i skonfigurowac srodowisko za pomoca flutter doctor
✅ Zorganizowac projekt wedlug funkcjonalnosci dla lepszej organizacji
✅ Uzywac Riverpod do typowanego i bezpiecznego zarzadzania stanem
✅ Skonfigurowac GoRouter z przekierowaniami uwierzytelniania
✅ Tworzyc wielokrotnego uzytku i kompozycyjne widgety
✅ Wdrozyc spojny motyw Material 3
✅ Centralizowac wywolania HTTP za pomoca Dio i interceptorow

Zacznij ćwiczyć!

Sprawdź swoją wiedzę z naszymi symulatorami rozmów i testami technicznymi.

Utwórz darmowe konto

Deklaratywne podejscie Fluttera sprzyja kompozycji i wielokrotnemu uzytku. Kazdy widget moze byc testowany niezaleznie, a hot-reload znaczaco przyspiesza cykl rozwoju. Ta solidna baza pozwala rozszerzac aplikacje o zaawansowane funkcjonalnosci, takie jak zlozone animacje, automatyczne testowanie i wdrazanie w sklepach z aplikacjami.

Flutter: Budowanie pierwszej aplikacji wieloplatformowej