Swift Result.Publisher handleEvents(receiveSubscription:receiveOutput:receiveCompletion:receiveCancel:receiveRequest:)用法及代码示例

实例方法

handleEvents(receiveSubscription:receiveOutput:receiveCompletion:receiveCancel:receiveRequest:)

当发布者事件发生时执行指定的闭包。

声明

func handleEvents(
    receiveSubscription: ((Subscription) -> Void)? = nil,
    receiveOutput: ((Self.Output) -> Void)? = nil,
    receiveCompletion: ((Subscribers.Completion<Self.Failure>) -> Void)? = nil,
    receiveCancel: (() -> Void)? = nil,
    receiveRequest: ((Subscribers.Demand) -> Void)? = nil
) -> Publishers.HandleEvents<Self>

返回值

当发布者事件发生时执行指定关闭的发布者。

参数

receiveSubscription: 当发布者从上游发布者收到订阅时执行的可选闭包。此值默认为 nil 。
receiveOutput: 当发布者从上游发布者接收到值时执行的可选闭包。此值默认为 nil 。
receiveCompletion: 当上游发布者正常完成或因错误终止时执行的可选闭包。此值默认为 nil 。
receiveCancel: 当下游接收者取消发布时执行的可选闭包。此值默认为 nil 。
receiveRequest: 当发布者收到更多元素的请求时执行的可选闭包。此值默认为 nil 。

详述

采用Publisher/handleEvents(receiveSubscription:receiveOutput:receiveCompletion:receiveCancel:receiveRequest:)当您想要在发布者生命周期的各个阶段检查元素时。

在下面的示例中，整数发布者显示了在element-processing 生命周期的每个阶段打印调试信息的效果：


let integers = (0...2)
cancellable = integers.publisher
    .handleEvents(receiveSubscription: { subs in
        print("Subscription: \(subs.combineIdentifier)")
    }, receiveOutput: { anInt in
        print("in output handler, received \(anInt)")
    }, receiveCompletion: { _ in
        print("in completion handler")
    }, receiveCancel: {
        print("received cancel")
    }, receiveRequest: { (demand) in
        print("received demand: \(demand.description)")
    })
    .sink { _ in return }


// Prints:
//   received demand: unlimited
//   Subscription: 0x7f81284734c0
//   in output handler, received 0
//   in output handler, received 1
//   in output handler, received 2
//   in completion handler

可用版本

iOS 13.0+, iPadOS 13.0+, macOS 10.15+, Mac Catalyst 13.0+, tvOS 13.0+, watchOS 6.0+

相关用法

注：本文由纯净天空筛选整理自apple.com大神的英文原创作品 Result.Publisher handleEvents(receiveSubscription:receiveOutput:receiveCompletion:receiveCancel:receiveRequest:)。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。