ios - Controller 中泛型类的属性注入(inject)

Question

我在我的ios应用程序中构建了一个状态管理，类似于javascript中的redux。它可以工作，而且使用起来很好，但我想抽象和解耦框架中的某些部分，以实现可重用性、测试和共享。

要添加一些上下文，主要思想是创建一个 class store与 getState和dispatch方法。一个结构State用户定义的内容在商店初始化时传递。

/* Store signature: class MyStore<State>: MyStoreProcotol */

let store = MyStore(state: ApplicationState())`

商店初始化后，我尝试将其注入(inject)任何符合 ConnectionProtocol 的类(例如 UIViewController，但不是强制性的)。 。在下面的代码中，我将 Controller 和存储传递给函数 injectStoreInView 。我正在尝试通过此函数将存储注入(inject) Controller 中，func injectStoreInView<State>(viewController: UIViewController, store: MyStore<State>)

我尝试了几种使用泛型的方法，但没有成功。我已阅读“类型删除”并遵循教程，但我不确定它是否对这种情况有帮助以及如何应用它。我在处理参数 store 的类型时遇到麻烦的injectStoreInView，并且以后无法在 Controller 中分配它controller.connection.store .

这是代码，其中很多部分已被删除以说明问题。 (此代码不起作用。)

框架部分:

import UIKit

/* store */

protocol MyStoreProcotol {

  associatedtype State

  func getState() -> State

}

class MyStore<State>: MyStoreProcotol {

  var state: State

  init(state: State) {
    self.state = state
  }

  func getState() -> State {
    return self.state
  }

}

/* connection */

protocol ConnectionProtocol {

  associatedtype State

  var connection: Connection<State> { get }

}

class Connection<State> {
  var store: MyStore<State>? = nil
}

func injectStoreInView<State>(
  viewController: UIViewController,
  store: MyStore<State>
) {
  if let controller = viewController /* as ConnectionProtocol */ {
    controller.connection.store = store

    print("yeah !")
  }
}

在应用程序部分:

struct ApplicationState {
  var counter = 0
}

class StartViewConnector: UIViewController, ConnectionProtocol {

  let connection = Connection<ApplicationState>()

}

func appDelegatedidFinishLaunchingWithOptions() -> Bool {

  let store = MyStore(state: ApplicationState())

  let controller = StartViewConnector() // connector can be any class who conform to ConnectionProtocol, StartViewConnector for test but self.window?.rootViewController in iOS App

  injectStoreInView(viewController: controller, store: store)

  return true
}

appDelegatedidFinishLaunchingWithOptions()

Answer 1

按照@Brandon关于linkedTypes和protocolInjection的建议解决了这个问题。他在评论中提供的链接非常有帮助( How to create generic protocols in Swift? )。

此代码有效:

框架:

import UIKit

/* store */

protocol MyStoreProcotol {

  associatedtype State

  func getState() -> State

}

class MyStore<State>: MyStoreProcotol {

  var state: State

  init(state: State) {
    self.state = state
  }

  func getState() -> State {
    return self.state
  }

}

/* connection */

protocol Connectable {

  associatedtype Store

  var connection: Connection<Store> { get }

}

protocol ConnectionProtocol {

  associatedtype Store

  var store: Store? { get set }

}

class Connection<Store>: ConnectionProtocol {

  var store: Store? = nil

}

func injectStoreInView
<
  Store: MyStoreProcotol,
  Controller: Connectable
>
(
  viewController: Controller,
  store: Store
) where Controller.Store == Store
{
  viewController.connection.store = store
}

在应用程序中的用法:

struct ApplicationState {
  var counter = 0
}

class StartViewConnector: UIViewController, Connectable {

  let connection = Connection<MyStore<ApplicationState>>()

}

func appDelegatedidFinishLaunchingWithOptions() -> Bool {

  let store = MyStore(state: ApplicationState())

  let connector = StartViewConnector()

  injectStoreInView(viewController: connector, store: store)

  // Now the store is properly injected, connector.connection.store = store

  return true
}

appDelegatedidFinishLaunchingWithOptions()