完成 Combine 后如何再次订阅？

Question

订阅后，我用send方法完成了订阅
我重新订阅了，但是已经结束了。如何重新订阅？

import Combine

let subject = PassthroughSubject<String, Never>()

subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test1")
subject.send(completion: .finished)


subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test2")

输出结果如下

Received value: test1
Received completion: finished
Received completion: finished

如何获取“接收值：test2”？

Answer 1

它是 rx 编程的概念，并不特定于 combine。我建议你学习基础。 https://rxmarbles.com

当您收到完成事件或错误事件时，流就结束了它的生命。之后不会再有活动了。

你可以想象这就像流的死亡。不要让它死去或诞生新的来取代它。

Answer 2

发送完成后，发布者就完成了。因此，如果您想再次订阅并获取新事件，您将需要该发布者的 新实例。

var subject = PassthroughSubject<String, Never>() //<-- var instead of let

subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test1")
subject.send(completion: .finished)

subject = PassthroughSubject<String, Never>() //<-- Here

subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test2")

完成 Combine 后如何再次订阅？

How can I subscribe again after finishing with Combine?

swift

combine

completion