Hookable.swift

Hookable.swift

protocol Hookable {
  associatedtype HookModelType
  var hook: PublishRelay<HookModelType> { get }
}

private var hookKey: String = "hook"
extension Hookable {
  
  var hook: PublishRelay<HookModelType> {
    get {
      if let value = objc_getAssociatedObject(self, &hookKey) as? PublishRelay<HookModelType> {
        return value
      }
      
      let hook: PublishRelay<HookModelType> = PublishRelay()
      
      objc_setAssociatedObject(self,
                               &hookKey,
                               hook,
                               objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN_NONATOMIC)
      return hook
    }
  }
}

HookModelProtocol.swift

protocol HookModelProtocol {
  associatedtype HookModel
}

HookUserCase.swift

enum HookUserCase: HookModelProtocol {
  
  enum HookModel {
    case article(Article)
    case user(User)
  }
  
  struct Article {
    let name: String
  }
  
  struct User {
    let id: Int
  }
}

ViewController.swift

class ViewController: UIViewController, Hookable {

  typealias HookModelType = HookUserCase.HookModel
  
  var disposeBag: DisposeBag = .init()

  deinit {
    debugPrint("DEINIT: ViewController")
  }
  
  override func viewDidLoad() {
    super.viewDidLoad()
    
    hook.asObservable()
      .map { hook -> HookUserCase.Article? in
        guard case HookUserCase.HookModel.article(let value) = hook else { return nil }
        return value
      }
      .filter { $0 != nil }
      .debug("article")
      .subscribe()
      .disposed(by: disposeBag)
    
    hook.asObservable()
      .map { hook -> HookUserCase.User? in
        guard case HookUserCase.HookModel.user(let value) = hook else { return nil }
        return value
      }
      .filter { $0 != nil }
      .debug("user")
      .subscribe()
      .disposed(by: disposeBag)
    
    hook.accept(HookModelType.article(HookUserCase.Article.init(name: "test")))
    hook.accept(HookModelType.user(.init(id: 20)))
    
    DispatchQueue.main.asyncAfter(deadline: .now() + 5) {
      UIApplication.shared.keyWindow?.rootViewController = nil
    }
  }
}