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我不確定如何進行以下工作。 （Swift 3，XCode8）。Swift 3中的泛型強制
我想製作一個通用節點類，它將狀態對象和/或線框對象作爲通用參數與狀態對象的協議約束爲NodeState。
我得到以下錯誤：
Cannot convert value of type Node<State, Wireframe> to type Node<_,_> in coercion
用下面的代碼（應在遊樂場工作）：
import Foundation
public protocol NodeState {
associatedtype EventType
associatedtype WireframeType
mutating func action(_ event: EventType, withNode node: Node<Self, WireframeType>)
}
extension NodeState {
mutating public func action(_ event: EventType, withNode node: Node<Self, WireframeType>) { }
}
public class Node<State: NodeState, Wireframe> {
public var state: State
public var wireframe: Wireframe?
public init(state: State, wireframe: Wireframe?) {
self.state = state
guard wireframe != nil else { return }
self.wireframe = wireframe
}
public func processEvent(_ event: State.EventType) {
DispatchQueue.main.sync { [weak self] in
// Error presents on the following
let node = self! as Node<State, State.WireframeType>
self!.state.action(event, withNode: node)
}
}
}
任何幫助將不勝感激。謝謝！
UPDATE：
以下工作 - 當我刪除了線框引用：
import Foundation
public protocol NodeState {
associatedtype EventType
mutating func action(_ event: EventType, withNode node: Node<Self>)
}
extension NodeState {
mutating public func action(_ event: EventType, withNode node: Node<Self>) { }
}
public class Node<State: NodeState> {
public var state: State
public init(state: State) {
self.state = state
}
public func processEvent(_ event: State.EventType) {
DispatchQueue.main.sync { [weak self] in
self!.state.action(event, withNode: self!)
}
}
}
現在，如何添加選項添加一個通用的線框對象到Node類？
爲什麼你需要一個單獨的'Wireframe'泛型參數？你不能只在類中使用'State.WireframeType'類型嗎？ – Hamish
感謝Hamish，這是有效的。 –