ios – ReactiveX如何暂停observable

2024年1月26日 194次阅读

我在iOS /
Swift(
RxSwift)中使用
ReactiveX.

假设我有一个可观察的：

let dataUpdates = ...

我订阅的是：

dataUpdates.subscribeNext({ data in
    // update tableView with data
    // maybe move to a difference cell with an animation
})

如果我在动画时收到更新,我不希望在动画结束之前收到下一个更新(我不想丢失动画期间发生的更新).

所以我需要的是暂停发出dataUpdates的可观察性.

我怎样才能做到这一点？

最佳答案 使用BehaviorSubject创建一个暂停和恢复更新的阀门.请注意,您需要在dataUpdates中获得一些背压支持(即缓冲),以获取阀门关闭时到达的更新.

所以在伪代码中(我不编码switft,所以请原谅我的语法)

// create a BehaviorSubject with default value true. It will always emit
// the latest value when subscribed to, thus it is kind of a variable
let valve = BehaviorSubject(value: true)

// we are only interested to get one `true` value. When the latest value
// received by the valve is `true`, this will give a value immediately when
// subscribed to. When the latest value is `false`, this will not give
// any events until it is true.
let openValve = valve.filter{$0}.take(1)

// for each data update, pass it through if the valve is open and otherwise
// start waiting for it to turn true
let pauseableDataUpdates = dataUpdates.concatMap{update in openValve.map { _ in update}}

// now when you start rendering, you do
valve.on(.Next(false))

// and after animation is done, you do
valve.on(.Next(true))
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