ios - 如何使用 swinject 正确注入(inject)依赖项

Question

我正在尝试使用 Swinject 注入(inject)依赖项，但我不知道自己做错了什么。

我有处理注册字符串用户的协议(protocol)。

protocol AuthServiceProtocol {
func registerUser(email: String, password: String, completion: @escaping CompletionHandler) }

和一个符合这个协议(protocol)的类使得所有的逻辑:

class AuthService: AuthServiceProtocol {
func registerUser(email: String, password: String, completion: @escaping CompletionHandler) {

        let lowerCaseMail = email.lowercased()
        let body: [String: Any] = [
            "email": lowerCaseMail,
            "password" : password
        ]

        Alamofire.request(URL_REGISTER, method: .post, parameters: body, encoding: JSONEncoding.default, headers: HEADER).responseString { (response) in
            if response.result.error == nil {
                completion(true)
            } else {
                completion(false)
                debugPrint(response.result.error as Any)
            }
        }
    }
} 

所以，在 AppDelegate 中我们注册容器，它看起来像:

let container = Container() { container in
    container.register(AuthServiceProtocol.self) { _ in AuthService() }.inObjectScope(.container)
    container.register(CreateAccountVC.self) { r in
        let controller = CreateAccountVC()
        controller.authService = r.resolve(AuthServiceProtocol.self)
        return controller
    }
}

但在 CreateAccountVC 中 authService 是空的。任何想法我该怎么做？CreateAccountVC 是 ViewController 的子类，我已经通过属性和构造函数对其进行了尝试，但它一直都是 nil。

Answer 1

检查你的代码:

var container : Container {
        let container = Container()
        container.register(AuthServiceProtocol.self) { _ in AuthService() }.inObjectScope(.container)
        container.register(CreateAccountVC.self) { r in
            let controller = CreateAccountVC()
            controller.authService = r.resolve(AuthServiceProtocol.self)
            print(r.resolve(AuthServiceProtocol.self))
            return controller
        }

        return container
    }

您有计算属性，每次调用它时，它都会创建一个新的 Container 对象。

重构您的代码以拥有单个容器，我相信您会顺利进行。

---

编辑:

这是一个有效的代码片段。下面是一个抽象具体 DI 服务的小包装类(以防 Swinject 有一天被其他东西取代):

import Swinject

public class ConfigurationProvider {

    // Currently using Swinject
    private let backingService = Container()

    // Singleton
    public static let shared = ConfigurationProvider()

    // Hidden initializer
    private init() {}


    // MARK: - Bind / Resolve

    public func bind<T>(interface: T.Type, to assembly: T) {
        backingService.register(interface) { _ in assembly }
    }

    public func resolve<T>(interface: T.Type) -> T! {
        return backingService.resolve(interface)
    }
}


// Extension methods to ignore 'shared.' call, like:
// ConfigurationProvider.bind(interface: IAssembly, to: Assembly())
// ConfigurationProvider.resolve(interface: IAssembly)

public extension ConfigurationProvider {

    static func bind<T>(interface: T.Type, to assembly: T) {
        ConfigurationProvider.shared.bind(interface: interface, to: assembly)
    }

    static func resolve<T>(interface: T.Type) -> T! {
        return ConfigurationProvider.shared.resolve(interface: interface)
    }
}

用法:

class RSAuthLoginModuleAssembly: IAuthLoginModuleAssembly {

}

// Register:

ConfigurationProvider.bind(interface: IAuthLoginModuleAssembly.self, to: ConcreteAuthLoginModuleAssembly())

// Resolve:

    guard let assembly = ConfigurationProvider.resolve(interface: IAuthLoginModuleAssembly.self) else {
        throw NSError(domain: "Assembly cannot be nil", code: 999, userInfo: nil)
    }