Dependency Injection with Storyboard

dependecyInjectionStoryboard.swift

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var window: UIWindow?
    
    func applicationDidFinishLaunching(_ application: UIApplication) {
        if let navigationController = window?.rootViewController as? UINavigationController,
            let breatherViewController = navigationController.topViewController as? BreatherViewController {
                // Property and initialiser injection in one line
                breatherViewController.dataSource = BreatherDataSource(with: NetworkClient())
        }
    }
}

// needs property injection
class BreatherViewController: UIViewController {
    // Dependencies
    var dataSource: BreatherDataSource?
      
    override func viewDidLoad() {
        super.viewDidLoad()
        print(dataSource) // spoiler: not nil!
    }
}

// needs initialiser injection
class BreatherDataSource {
    // Dependencies
    private let networkClient: NetworkClient?
    
    init(with networkClient: NetworkClient) {
        self.networkClient = networkClient
    }
}