在Publisher上执行副作用 [英] Performing side effects on Publisher

问题描述

我正在尝试在 Publisher 上执行副作用，但找不到任何允许我执行类似操作的运算符.确切地说，我正在寻找与RxSwift的 do(on:)类似的概念.

I'm trying to perform side effect on Publisher, and I can't find any operator which will allow me to do something like this. To be precise, I'm looking for a concept similar to RxSwift's do(on:).

这就是我想要做的.我正在为第三方SDK提供的委托编写反应式包装.它是用于与BLE设备进行交互的SDK.我有 startScanning 和 stopScanning 之类的方法，而我想要实现的是对信号做出反应并调用 stopScanning 作为任何错误或副作用的副作用.完成事件.到目前为止，我有这样的事情:

Here's what I'm trying to do. I'm writing a reactive wrapper for a delegate provided by a 3rd party SDK. It's and SDK for interacting with BLE devices. I have methods like startScanning and stopScanning and what I want to achieve is to react to signals and call stopScanning as a side effect of any error or complete events. So far, I have something like this:

newDeviceFoundPublisher
            .timeout(.seconds(timeout), scheduler: DispatchQueue.global())
            .eraseToAnyPublisher()

我想要实现的是这样的:

and what I want to achieve is something like:

newDeviceFoundPublisher
            .timeout(.seconds(timeout), scheduler: DispatchQueue.global())
            .doOnError {
                manager.stopScanning()
            }
            .doOnComplete {
                manager.stopScanning()
            }
            .eraseToAnyPublisher()

是否已经有类似的东西，或者我丢失了某些东西，并且在Combine中有一些东西我可以使用并获得结果?

Is there already something like this or maybe I'm missing something, and there's something in Combine I can use and get the result?

推荐答案

您可能正在寻找 .handleEvents 运算符.您可以使用五个不同参数中的任何一个来实现它.它们都是可选的，因此仅实现您需要的那些.错误和完成都将计为 receiveCompletion:.

You might be looking for the .handleEvents operator. You can implement it with any of five different parameters; they are all optional, so implement just those you need. Both an error and a completion would count as receiveCompletion:.

请注意，如果您不 catch ，该错误仍将继续沿流水线传播！(无论如何，完成都会顺着管道进行，我认为您不能停止它.)

Note that the error will still flow on down the pipeline if you don't catch it! (The completion will flow down the pipeline in any case, and I don't think you can stop it.)

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