九、可连接的操作-Connectable Operators(Rx.playground翻译)

注意：使用本例中的代码首先应该导入头文件，代码如下：

import RxSwift

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Connectable Operators

可连接的Observable序列类似于普通的Observable序列，除了当它们被订阅后一开始不发散元素，只有当它们的connect方法被调用才会发散元素。这样，你可以等待所有的订阅者在可连接的Observable序列开始发散元素之前订阅它。

在本页的每个例子中都有一个注释掉的方法。�运行例子需要取消注释，停止运行需要注释掉。

在学习关于可连接的Observable序列的知识之前，让我看一个不是可连接的�操作：

func sampleWithoutConnectableOperators() {
    printExampleHeader(#function)

    let interval = Observable.interval(1, scheduler: MainScheduler.instance)
    _ = interval
        .subscribeNext { print("Subscription: 1, Event: \($0)") }

    delay(5) {
        _ = interval
            .subscribeNext { print("Subscription: 2, Event: \($0)") }
    }
}
//sampleWithoutConnectableOperators() //  Uncomment to run this example; comment to stop running

在指定的调度程序之上，interval(间隔)创建一个Observable序列并且在每个period(周期)之后发散元素。了解更多

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publish

把源Observable序列转换成一个可连接的Observable序列。�了解更多

func sampleWithPublish() {
    printExampleHeader(#function)

    let intSequence = Observable.interval(1, scheduler: MainScheduler.instance)

    _ = intSequence
        .subscribeNext { print("Subscription: 1, Event: \($0)") }

    delay(2) { intSequence.connect() }

    delay(4) {
        _ = intSequence
            .subscribeNext { print("Subscription: 2, Event: \($0)") }
    }

    delay(6) {
        _ = intSequence
            .subscribeNext { print("Subscription: 3, Event: \($0)") }
    }
}

//sampleWithPublish() //  Uncomment to run this example; comment to stop running

调度程序�作为一个抽象机制来执行工作,比如在特定线程或调度队列。�了解等多

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replay

把源Observable序列转换成一个可连接的Observable序列，并且将重复�发散bufferSize次。�了解更多

func sampleWithReplayBuffer() {
    printExampleHeader(#function)
    
    let intSequence = Observable.interval(1, scheduler: MainScheduler.instance)
        .replay(5)
    
    _ = intSequence
        .subscribeNext { print("Subscription 1:, Event: \($0)") }
    
    delay(2) { intSequence.connect() }
    
    delay(4) {
        _ = intSequence
            .subscribeNext { print("Subscription 2:, Event: \($0)") }
    }
    
    delay(8) {
        _ = intSequence
            .subscribeNext { print("Subscription 3:, Event: \($0)") }
    }
}

// sampleWithReplayBuffer() //  Uncomment to run this example; comment to stop running

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multicast

把源Observable序列转换成一个可连接的Observable序列，并通过指定的subject广播发散。

func sampleWithMulticast() {
    printExampleHeader(#function)
    
    let subject = PublishSubject()
    
    _ = subject
        .subscribeNext { print("Subject: \($0)") }
    
    let intSequence = Observable.interval(1, scheduler: MainScheduler.instance)
        .multicast(subject)
    
    _ = intSequence
        .subscribeNext { print("\tSubscription 1:, Event: \($0)") }
    
    delay(2) { intSequence.connect() }
    
    delay(4) {
        _ = intSequence
            .subscribeNext { print("\tSubscription 2:, Event: \($0)") }
    }
    
    delay(6) {
        _ = intSequence
            .subscribeNext { print("\tSubscription 3:, Event: \($0)") }
    }
}

//sampleWithMulticast() // Uncomment to run this example; comment to stop running

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