What is the use of yield in flutter proviide me with some real world example ?

yield in Flutter/Dart

yield enables creating generator functions that return values one at a time.

Basic yield

dartCopy
Stream<int> countUp() async* {
  for (int i = 1; i <= 5; i++) {
    await Future.delayed(Duration(seconds: 1));
    yield i;
  }
}

void main() {
  countUp().listen((value) => print(value));
  // Prints: 1, 2, 3, 4, 5 (with 1 second delays)
}

Real-world: Data Streaming

dartCopy
Stream<User> fetchUsersStream() async* {
  final response = await http.get(Uri.parse('/api/users'));
  final users = jsonDecode(response.body) as List;
  
  for (var userData in users) {
    yield User.fromJson(userData);
    await Future.delayed(Duration(milliseconds: 100));
  }
}

// Usage in UI
StreamBuilder<User>(
  stream: fetchUsersStream(),
  builder: (context, snapshot) {
    if (snapshot.hasData) return Text(snapshot.data!.name);
    if (snapshot.hasError) return Text('Error');
    return CircularProgressIndicator();
  },
)

yield with Pagination

dartCopy
Stream<List<Product>> fetchProductsStream(int pageSize) async* {
  int page = 0;
  while (true) {
    final products = await fetchPage(page, pageSize);
    if (products.isEmpty) break;
    yield products;
    page++;
  }
}

Use: Streaming data over time, pagination, real-time updates.