SwiftUI Combine Framework 共享receiveCompletion 代码块

Posted 2023-02-24

【中文标题】SwiftUI Combine Framework 共享receiveCompletion 代码块

【英文标题】：SwiftUI Combine Framework shared receiveCompletion code block

【发布时间】：2021-06-29 13:48:58

【问题描述】：

在 SwiftUI 订阅者中，您通常会拥有这个

authenticate
    .receive(on: DispatchQueue.main) // Move to the main thread
    .sink(receiveCompletion:  completion in
        switch completion 
        case .failure(let error): ()
        case .finished: ()
        
    , receiveValue:  _ in )

我想提取要在多个订阅者之间共享的 receiveCompletion 代码块，期望相同的完成，即下面要分开并在多个订阅者中使用。

receiveCompletion:  completion in
            switch completion 
            case .failure(let error): ()
            case .finished: ()
            

【问题讨论】：

您可以简单地为“receiveCompletion”创建一个单独的函数并将该函数传递到任何地方。

@andykkt，我似乎做得不对。然而，要正确地将我的手包裹在封闭物周围。请帮忙

一个（可能很有趣）旁注：如果错误的类型是Never，您可以省略receiveCompletion 部分（以防您只对接收新值感兴趣）。您可以通过将错误映射到某个值来实现这一点（可能是nil）

【参考方案1】：

你可以只写简单的函数来封装逻辑：

extension Publisher where Failure == Never 

    public func sinkOnMain(
        receiveValue: @escaping ((Self.Output) -> Void)) -> AnyCancellable 

        receive(on: RunLoop.main)
            .sink(receiveValue: receiveValue)
    


extension Publisher 

    public func sinkOnMain(
        receiveCompletion: @escaping ((Subscribers.Completion<Self.Failure>) -> Void),
        receiveValue: @escaping ((Self.Output) -> Void)) -> AnyCancellable 

        receive(on: RunLoop.main)
            .sink(receiveCompletion: receiveCompletion, receiveValue: receiveValue)
    

它们都与普通的sink 做同样的工作，但首先将执行移至主运行循环。

【参考方案2】：

这就是我要找的东西

static func handleCompletion(completion: Subscribers.Completion<Error>) 
        switch completion 
        case .failure(let error): ()
        case .finished: ()
        
    

那就这样称呼吧

authenticate
    .receive(on: DispatchQueue.main) // Move to the main thread
    .sink(receiveCompletion: handleCompletion
    , receiveValue:  _ in )