pattern-sink.adoc

使用 sink 创建一个订阅者

目的

• 要接收来自发布者或管道生成的输出以及错误或者完成消息，你可以使用 sink 创建一个订阅者。

参考

• sink

另请参阅

• patterns.adoc

• patterns.adoc

• patterns.adoc

代码和解释

Sink 创建了一个通用订阅者来捕获或响应来自 Combine 管道的数据，同时支持取消和 coreconcepts.adoc。

简单的 sink 例子

let cancellablePipeline = publishingSource.sink { someValue in (1)
    // do what you want with the resulting value passed down
    // be aware that depending on the publisher, this closure
    // may be invoked multiple times.
    print(".sink() received \(someValue)")
})

1. 简单版本的 sink 是非常简洁的，跟了一个尾随闭包来接收从管道发送来的数据。

带有完成事件和数据的 sink

let cancellablePipeline = publishingSource.sink(receiveCompletion: { completion in (1)
    switch completion {
    case .finished:
        // no associated data, but you can react to knowing the
        // request has been completed
        break
    case .failure(let anError):
        // do what you want with the error details, presenting,
        // logging, or hiding as appropriate
        print("received the error: ", anError)
        break
    }
}, receiveValue: { someValue in
    // do what you want with the resulting value passed down
    // be aware that depending on the publisher, this closure
    // may be invoked multiple times.
    print(".sink() received \(someValue)")
})

cancellablePipeline.cancel() (2)

1. Sinks 是通过发布者或管道中的代码链创建的，并为管道提供终点。 当 sink 在发布者创建或调用时，它通过 subscribe 方法隐式地开始了 coreconcepts.adoc，并请求无限制的数据。

2. Sinks 是可取消的订阅者。在任何时候，你可以使用 sink 末端对其的引用，并在上面调用 .cancel() 来使管道失效并关闭管道。

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