ReactiveX如何暂停可观察对象

Question

我在iOS/Swift (RxSwift)中使用ReactiveX。

假设我有一个观察值：

let dataUpdates = ...

我已经订阅了：

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

如果我在动画中收到更新，我不想在动画结束之前收到下一次更新(我也不想丢失动画过程中发生的更新)。

所以我需要做的就是暂停dataUpdates的发射。

我如何才能做到这一点？

Answer 1

使用BehaviorSubject创建暂停和恢复更新的阀。请注意，当阀门关闭时，您将需要在dataUpdates中提供一些背压支持(即缓冲)，以便进行更新。

所以在伪代码中(我没有编写switft代码，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))