實例方法
share()
與多個訂閱者共享上遊發布者的輸出。
聲明
func share() -> Publishers.Share<Self>
返回值
一個類實例,它將從其上遊接收到的元素共享給多個訂閱者。
詳述
該操作符返回的發布者支持多個訂閱者,所有訂閱者都從上遊發布者接收未更改的元素和完成狀態。
以下示例使用序列發布者作為計數器發布三個隨機數,由 Publisher/map(_:)-99evh
運算符生成。它使用Publisher/share()
運算符向兩個訂閱者中的每一個共享相同的隨機數。此示例僅使用 Publisher/delay(for:tolerance:scheduler:options:)
運算符來防止第一個訂閱者立即耗盡序列發布者;異步發布者不需要這個。
let pub = (1...3).publisher
.delay(for: 1, scheduler: DispatchQueue.main)
.map( { _ in return Int.random(in: 0...100) } )
.print("Random")
.share()
cancellable1 = pub
.sink { print ("Stream 1 received: \($0)")}
cancellable2 = pub
.sink { print ("Stream 2 received: \($0)")}
// Prints:
// Random: receive value: (20)
// Stream 1 received: 20
// Stream 2 received: 20
// Random: receive value: (85)
// Stream 1 received: 85
// Stream 2 received: 85
// Random: receive value: (98)
// Stream 1 received: 98
// Stream 2 received: 98
如果沒有 Publisher/share()
運算符,流 1 會接收三個隨機值,然後流 2 會接收三個不同的隨機值。
另請注意,Publishers/Share
是一個類,而不是像大多數其他發布者那樣的結構。這意味著您可以使用此運算符創建使用引用語義的發布者實例。
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
- Swift Optional.Publisher sink(receiveValue:)用法及代碼示例
- Swift Optional.Publisher scan(_:_:)用法及代碼示例
- Swift Optional.Publisher sink(receiveCompletion:receiveValue:)用法及代碼示例
- Swift Optional.Publisher setFailureType(to:)用法及代碼示例
- Swift Optional.Publisher subscribe(on:options:)用法及代碼示例
- Swift Optional.Publisher reduce(_:_:)用法及代碼示例
- Swift Optional.Publisher tryDrop(while:)用法及代碼示例
- Swift Optional.Publisher debounce(for:scheduler:options:)用法及代碼示例
- Swift Optional.Publisher breakpoint(receiveSubscription:receiveOutput:receiveCompletion:)用法及代碼示例
- Swift Optional.Publisher mapError(_:)用法及代碼示例
- Swift Optional.Publisher catch(_:)用法及代碼示例
- Swift Optional.Publisher tryAllSatisfy(_:)用法及代碼示例
- Swift Optional.Publisher zip(_:_:_:)用法及代碼示例
- Swift Optional.Publisher throttle(for:scheduler:latest:)用法及代碼示例
- Swift Optional.Publisher assertNoFailure(_:file:line:)用法及代碼示例
- Swift Optional.Publisher collect(_:)用法及代碼示例
- Swift Optional.Publisher combineLatest(_:_:_:_:)用法及代碼示例
- Swift Optional.Publisher merge(with:_:_:)用法及代碼示例
- Swift Optional.Publisher map(_:_:)用法及代碼示例
- Swift Optional.Publisher assign(to:on:)用法及代碼示例
- Swift Optional.Publisher zip(_:_:_:_:)用法及代碼示例
- Swift Optional.Publisher output(in:)用法及代碼示例
- Swift Optional.Publisher tryReduce(_:_:)用法及代碼示例
- Swift Optional.Publisher map(_:_:_:)用法及代碼示例
- Swift Optional.Publisher prepend(_:)用法及代碼示例
注:本文由純淨天空篩選整理自apple.com大神的英文原創作品 Optional.Publisher share()。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。