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

實例方法

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

當發布者事件發生時執行指定的閉包。

聲明

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

當發布者事件發生時執行指定關閉的發布者。

參數

receiveSubscription: 當發布者從上遊發布者收到訂閱時執行的可選閉包。此值默認為 nil 。
receiveOutput: 當發布者從上遊發布者接收到值時執行的可選閉包。此值默認為 nil 。
receiveCompletion: 當上遊發布者正常完成或因錯誤終止時執行的可選閉包。此值默認為 nil 。
receiveCancel: 當下遊接收者取消發布時執行的可選閉包。此值默認為 nil 。
receiveRequest: 當發布者收到更多元素的請求時執行的可選閉包。此值默認為 nil 。

詳述

采用Publisher/handleEvents(receiveSubscription:receiveOutput:receiveCompletion:receiveCancel:receiveRequest:)當您想要在發布者生命周期的各個階段檢查元素時。

在下麵的示例中，整數發布者顯示了在element-processing 生命周期的每個階段打印調試信息的效果：


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+

相關用法

注：本文由純淨天空篩選整理自apple.com大神的英文原創作品 Result.Publisher handleEvents(receiveSubscription:receiveOutput:receiveCompletion:receiveCancel:receiveRequest:)。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。