Développeur Application Mobile Genève 2026 : Guide Recrutement & Tarifs

// Exemple Code Junior (Interview)
// Task : Fetch users API, display TableView

struct User: Codable {
    let id: Int
    let name: String
    let email: String
}

class UsersViewController: UIViewController {
    var users: [User] = []
    let tableView = UITableView()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupTableView()
        fetchUsers()
    }
    
    func fetchUsers() {
        // Junior souvent oublie error handling, completion handlers
        guard let url = URL(string: "https://api.example.com/users") else { return }
        
        URLSession.shared.dataTask(with: url) { data, response, error in
            guard let data = data else { return }
            
            if let users = try? JSONDecoder().decode([User].self, from: data) {
                self.users = users
                
                // 🚫 ERREUR CLASSIQUE JUNIOR : Update UI hors main thread
                self.tableView.reloadData()  // ← Crash potentiel
            }
        }.resume()
    }
}

// Exemple Code Mid-Level (Architecture MVVM)

// Network Service (Separation of concerns)
protocol NetworkServiceProtocol {
    func fetchUsers() async throws -> [User]
}

class NetworkService: NetworkServiceProtocol {
    func fetchUsers() async throws -> [User] {
        guard let url = URL(string: "https://api.example.com/users") else {
            throw NetworkError.invalidURL
        }
        
        let (data, response) = try await URLSession.shared.data(from: url)
        
        guard let httpResponse = response as? HTTPURLResponse,
              (200...299).contains(httpResponse.statusCode) else {
            throw NetworkError.serverError
        }
        
        return try JSONDecoder().decode([User].self, from: data)
    }
}

// ViewModel (Business logic séparée UI)
@MainActor
class UsersViewModel: ObservableObject {
    @Published var users: [User] = []
    @Published var isLoading = false
    @Published var errorMessage: String?
    
    private let networkService: NetworkServiceProtocol
    
    // Dependency injection (testable)
    init(networkService: NetworkServiceProtocol = NetworkService()) {
        self.networkService = networkService
    }
    
    func loadUsers() {
        Task {
            isLoading = true
            errorMessage = nil
            
            do {
                users = try await networkService.fetchUsers()
            } catch {
                errorMessage = "Failed to load: \(error.localizedDescription)"
            }
            
            isLoading = false
        }
    }
}

// View (SwiftUI - Clean, declarative)
struct UsersView: View {
    @StateObject private var viewModel = UsersViewModel()
    
    var body: some View {
        NavigationView {
            Group {
                if viewModel.isLoading {
                    ProgressView()
                } else if let error = viewModel.errorMessage {
                    Text(error).foregroundColor(.red)
                } else {
                    List(viewModel.users, id: \.id) { user in
                        VStack(alignment: .leading) {
                            Text(user.name).font(.headline)
                            Text(user.email).font(.subheadline).foregroundColor(.gray)
                        }
                    }
                }
            }
            .navigationTitle("Users")
            .onAppear { viewModel.loadUsers() }
        }
    }
}