URLSession

1. GET Request

func fetchData() async throws -> [User] {
    let url = URL(string: "https://api.example.com/users")!
    let (data, _) = try await URLSession.shared.data(from: url)
    return try JSONDecoder().decode([User].self, from: data)
}

2. POST Request

func createUser(user: User) async throws {
    var request = URLRequest(url: URL(string: "https://api.example.com/users")!)
    request.httpMethod = "POST"
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    request.httpBody = try JSONEncoder().encode(user)

    let (_, response) = try await URLSession.shared.data(for: request)
    guard let httpResponse = response as? HTTPURLResponse,
          httpResponse.statusCode == 201 else {
        throw NetworkError.invalidResponse
    }
}

3. Trong ViewModel

@MainActor
class UsersViewModel: ObservableObject {
    @Published var users: [User] = []
    @Published var isLoading = false
    @Published var error: Error?

    func loadUsers() async {
        isLoading = true
        do {
            let url = URL(string: "https://api.example.com/users")!
            let (data, _) = try await URLSession.shared.data(from: url)
            users = try JSONDecoder().decode([User].self, from: data)
        } catch {
            self.error = error
        }
        isLoading = false
    }
}

4. Trong View

struct UsersView: View {
    @StateObject var viewModel = UsersViewModel()

    var body: some View {
        Group {
            if viewModel.isLoading {
                ProgressView()
            } else {
                List(viewModel.users) { user in
                    Text(user.name)
                }
            }
        }
        .task {
            await viewModel.loadUsers()
        }
    }
}

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📝 Key Points

• Dùng async/await cho network calls
• @MainActor cho ViewModel update UI
• .task modifier trong View
• Always handle errors