[英]Swift - Declaring an array of generics
I am struggling creating an array of generics in Swift. 我正在努力在Swift中创建泛型数组。 Here are my protocols / classes.
这是我的协议/类。
public protocol InitializableWithData {
init(data: NSData?) throws
}
internal struct RequestWithCompletionHandler<T: InitializableWithData> {
let request: APIRequest<T>
let completionHandler: ((response: APIResponse<T>?, error: Error?) -> Void)?
}
var ongoingRequests = [RequestWithCompletionHandler<InitializableWithData>]()
I get the following error: 我收到以下错误:
Using InitializableWithData as a concrete type conforming to protocol 'InitializableWithData' is not supported.
不支持将InitializableWithData用作符合协议“ InitializableWithData”的具体类型。
I am not interested in the actual type "contained" by RequestWithCompletionHandler
. 我对
RequestWithCompletionHandler
的实际类型“包含”不感兴趣。 I just want to keep track of all requests, without caring what entity they will "return". 我只想跟踪所有请求,而不关心它们将“返回”哪个实体。 I want to keep track of them so I can cancel them, pause them, etc.
我想跟踪它们,以便取消它们,暂停它们,等等。
So I want to keep track of all the ongoing requests so I can re execute them if necessary. 因此,我想跟踪所有正在进行的请求,以便在必要时可以重新执行它们。
The error message says you cannot use a protocol type ( InitializableWithData
) as concrete type (in RequestWithCompletionHandler<InitializableWithData>
). 错误消息指出您不能使用协议类型(
InitializableWithData
)作为具体类型(在RequestWithCompletionHandler<InitializableWithData>
)。
You need a concrete type conforming to the protocol like a struct for example 您需要一个符合协议的具体类型,例如struct
public protocol InitializableWithData {
init(data: NSData?) throws
}
internal struct RequestWithCompletionHandler<T: InitializableWithData> {
let request: APIRequest<T>
let completionHandler: ((response: APIResponse<T>?, error: Error?) -> Void)?
}
struct Test : InitializableWithData {
let data : NSData?
init(data: NSData?) throws {
self.data = data
}
}
var ongoingRequests = [RequestWithCompletionHandler<Test>]()
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