java - 快速覆盖方法

Question

我对在 swift 上搜索与此 java 代码等效的内容感到非常沮丧:

public abstract class BaseApiSubscriber<T> extends Subscriber<T> {
   private WeakReference<MvpView> mvpViewWeakReference;
   private WeakReference<BasePresenter> basePresenterWeakReference;

   public BaseApiSubscriber(BasePresenter basePresenter, MvpView mvpView) {
     this.basePresenterWeakReference = new WeakReference<>(basePresenter);
     this.mvpViewWeakReference = new WeakReference<>(mvpView);
   }

   @Override
   public void onCompleted() {
   }

   @Override
   public void onError(Throwable e) {
      //handle generic errors here, call also the mvpView to handle generic responses on UI
   }

   @Override
   public void onNext(T t) {
   }

基本上，我在这里扩展了 Subscriber，因此 API 的所有通用响应都在单个文件中处理。这适用于我的 java (android)，但我找不到如何使它在 swift 上工作。我尝试搜索extensions、protocols，但它们似乎无法扩展。我确实尝试过搜索，但我不知道这个的关键字，我尝试盲目编码(希望它会起作用)但我做不到。也许只是一个关键字、基本示例或对此的解释。我这样做对吗？也准备好接受反对票，因为我无法在 swift 上发布好的代码。它甚至离这个还差得很远。

更新: 感谢@luk2302，我以某种方式接近了它，但是我该如何实现呢？这是我的代码:

class BaseSubscriber: ObserverType {

typealias E = Response

func on(_ event: Event<Response>) {
    switch event {
    case .next(let _):
        print("Successing")
        break
    case .error(let error):
        print("Erorring")

        if let serviceError = error as? ServiceError {
            print("service error: " + serviceError.errorDescription!)
        }

        print(error)
        break
    case .completed:
        print("Completing")
        break
    }
}
}

然后我需要从这里调用它:

let base = BaseSubscriber()
repo.login(param: loginParam).subscribe(
     //Ive tried this:
     //base.on: {
     //}
     //but got an syntax error maybe hahahaha
)

这叫什么？所以我可以搜索和阅读它。谢谢。

更新 2: 感谢@Cristik，我已经设法做到了，通过传递一个闭包，我现在可以传递方法来为每个请求执行特定任务。我更新的代码:

func baseSubscriber<T>(mvpView: BaseMvpView, onNext: @escaping (T) -> Void, onError: @escaping (Error) -> Void, onCompleted: @escaping () -> Void)  -> (RxSwift.Event<T>) -> Void {
return { [weak mvpView] event in
    switch event {
    case let .next(element):
        mvpView?.hideLoading()
        print("super next")
        onNext(element)

    case .completed:
        mvpView?.hideLoading()
        print("super completed")
        onCompleted()

    case let .error(error):
        mvpView?.hideLoading()
        print("super error")
        if let serviceError = error as? ServiceError {
            print("Service error: \(serviceError.errorDescription ?? "Something wrong")")
        } else {
            onError(error)
        }
    }
}

但这与我在 java 上的方法不同，在 java 中我可以override onError() 方法，所以如果我想忽略一般错误处理，我可以做吧。如何将其应用于 swift？

更新 3:

BaseMvpView.swift

protocol BaseMvpView: class {

   func showLoading(message: String)

   func hideLoading()
}

BaseTableViewController.swift

class BaseTableViewController: UITableViewController, BaseMvpView {

var indicator: UIActivityIndicatorView?

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

override func viewDidLoad() {
    super.viewDidLoad()

    indicator = UIActivityIndicatorView(activityIndicatorStyle: UIActivityIndicatorViewStyle.gray)
    indicator?.frame = CGRect(origin: CGPoint.init(x: 0, y: 0), size: CGSize.init(width: 40, height: 40));
    indicator?.center = view.center
    view.addSubview(indicator!)
    indicator?.bringSubview(toFront: view)
    UIApplication.shared.isNetworkActivityIndicatorVisible = true
}

func showLoading(message: String) {
    indicator?.startAnimating()
}

func hideLoading() {
    indicator?.stopAnimating()
}
}

Answer 1

为此您不需要专门的类，似乎您唯一需要的是一个订阅者，它弱引用 View 和演示者，并处理常见的事件处理逻辑。

由于 RxSwift 订阅者也可以是一个带有一个 event 参数的闭包，你可以实现一个创建它的自由函数:

func customSubscriber<T>(mvpView: MvpView, presenter: BasePresenter) -> (RxSwift.Event<T>) -> Void {
    return { [weak mvpView, weak presenter] event in
        switch event {
        case let .next(element):
            print("Received \(element)")

        case .completed:
             print("Done")

        case let .error(error):
            if let serviceError = error as? ServiceError {
                print("Service error: \(serviceError)")
            } else {
                print("Some error: \(error)")
            }
        }
    }
}

你可以这样使用它:

myObserver.subscribe(customSubscriber(mvpView: someMvpView, presenter: somePresenter))

RxSwift 范式以闭包为中心:您从闭包创建观察者，订阅者是闭包，运算符使用闭包。同样在 Swift 中，结构和枚举(也称为值类型)等其他类型优于类(也称为引用类型)，它们只是在大多数情况下工作得更好。

更新 根据最新的片段，您似乎还希望允许基于接收者的不同事件处理。这可以通过使用具有默认实现的协议(protocol)来优雅地实现。

protocol Subscribable: class {
    associatedtype DataType

    func onNext(_ data: DataType)
    func onCompleted()
    func onError()
}

extension Subscribable where Self: BaseMvpView {
    func onNext(_ data: DataType) {
        hideLoading()
        print("super next")
    }

    func onCompleted() {
        hideLoading()
        print("super completed")
    }

    func onError() {
        hideLoading()
        print("super error")
        if let serviceError = error as? ServiceError {
            print("Service error: \(serviceError.errorDescription ?? "Something wrong")")
        }
    }
}

// BaseMvpView will get all above methos implemented, child classes can implement their own version.
extension BaseMvpView: Subscribable { 
    typealias DataType = DataTypeThatIsUsedByMvpView
}

// the subscriber function got simplifier as it no longer needs
// the callback parameters, as those are not part of the protocol
// this also makes the function more flexible as it's not tied to a
// concrete class
func baseSubscriber<S: Subscribable, T>(_ subscribable: S) -> (RxSwift.Event<T>) -> Void where S.DataType == T {
    return { [weak subscribable] event in
        switch event {
        case let .next(element):
            subscribable?.onNext(element)
        case .completed:
           subscribable.onCompleted()
        case let .error(error):
            subscribable.onError(error)
        }
    }
}

你可以这样调用新函数:

baseSubscriber(someMvpView)