Swift 协议要求方法返回协议

Question

我正在尝试编译以下代码。 基本上我希望对象符合多种协议，例如将不同组 API 暴露给应用程序不同部分的网络服务（例如：登录 API 到 loginController，共享 API 到 shareController）

+

我希望使用 networkXProvider 协议注入此服务，例如实现依赖注入（例如我想向 LoginController 传递一个采用 LoginControllerProvider 和 FetchingUsersFromDBProvider 的注入）：

protocol MyAccountCommunicator {
    func getAccountData() -> String
}

protocol EventsCommunicator {
    func getEvents() -> String
}


 class NetworkManager: MyAccountCommunicator, EventsCommunicator {
    func getAccountData() -> String {
        return "Accounts"
    }

    func getEvents() -> String {
        return "Events"
    }
}

protocol MyAccountCommunicatorProvider {
    var networkCommunicator: MyAccountCommunicator { get }
}


protocol EventsCommunicatorProvider {
    var networkCommunicator: EventsCommunicator { get }
}

class Injector: MyAccountCommunicatorProvider, EventsCommunicatorProvider {
    var networkCommunicator: NetworkManager = NetworkManager()
}

Playground 失败并出现以下错误：

错误：strings.playground:29:7：错误：类型“注射器”没有 符合协议'MyAccountCommunicatorProvider'类注入器： MyAccountCommunicatorProvider，EventsCommunicatorProvider { ^

strings.playground:30:9: 注意：候选人的类型不匹配 '网络管理员' var networkCommunicator: NetworkManager = NetworkManager() ^

错误：strings.playground:29:7：错误：类型“注射器”没有 符合协议'EventsCommunicatorProvider'类注入器： MyAccountCommunicatorProvider，EventsCommunicatorProvider { ^

strings.playground:30:9: 注意：候选人的类型不匹配 '网络管理员' var networkCommunicator: NetworkManager = NetworkManager()

环境：swift4、XCode9

Answer 1

为什么需要 MyAccountCommunicatorProvider 和 EventsCommunicatorProvider 协议？如果将它们合二为一呢？

protocol CommunicatorProvider {
 var networkCommunicator: NetworkManager { get }
}

class Injector: CommunicatorProvider {
   var networkCommunicator = NetworkManager()
}

Answer 2

    protocol MyAccountCommunicator {
    func getAccountData() -> String
}

protocol EventsCommunicator {
    func getEvents() -> String
}

protocol MyAccountCommunicatorProvider {
    var accountCommunicator: MyAccountCommunicator { get }
}

protocol EventsCommunicatorProvider {
    var eventCommunicator: EventsCommunicator { get }
}

class NetworkManager: MyAccountCommunicator, EventsCommunicator {
    func getAccountData() -> String {
        return "Accounts"
    }

    func getEvents() -> String {
        return "Events"
    }
}

class Injector: MyAccountCommunicatorProvider, EventsCommunicatorProvider {
    var networkManager = NetworkManager()
    var accountCommunicator: MyAccountCommunicator {
        return networkManager
    }

    var eventCommunicator: EventsCommunicator {
        return networkManager
    }
}

Answer 3

你可以这样使用：

protocol MyAccountCommunicatorProvider {
    var networkCommunicator1: MyAccountCommunicator { get }
}

protocol EventsCommunicatorProvider {
    var networkCommunicator2: EventsCommunicator { get }
}

class Injector: MyAccountCommunicatorProvider, EventsCommunicatorProvider {
    var networkCommunicator: NetworkManager = NetworkManager()
    lazy var networkCommunicator1: MyAccountCommunicator = {
        return networkCommunicator
    }()
    lazy var networkCommunicator2: EventsCommunicator = {
        return networkCommunicator
    }()
}