如何在条件变为真之前限制可观察的

Question

我的应用程序中有一个集合视图，当有新内容或删除内容时，它会以动画方式刷新。但是，我不希望它在用户滚动时刷新，因为这会导致抖动。我只想在用户完成滚动/不滚动时刷新集合视图。

所以我有一个数据源驱动程序，我尝试使用 filter 让它等到它变为 true 但没有运气。

这是我传递给 ViewModel

的滚动驱动程序

let isScrollViewScrollingDriver = Observable.merge(
            gridCollectionView.rx.willBeginDragging.map { _ in true },
            gridCollectionView.rx.didEndDragging.map { _ in false }
        ).asDriver(onErrorJustReturn: false).startWith(false).distinctUntilChanged()

我的 ViewModel 在视图控制器中初始化

viewModel = ViewModel(
            photoLibraryService: PhotoLibraryService.shared,
            isGridViewScrolling: isScrollViewScrollingDriver,
            disposeBag: disposeBag
        )

我的视图模型

let assetDriver = photoLibraryService.albumDriver.asObservable()
                .withLatestFrom(
                    isGridViewScrolling.asObservable().filter { [=12=] == false }
                ) { (arg0, arg1) in
                    return arg0
                }.flatMapLatest { libraryAlbum -> Observable<[LibraryAsset]> in
                    return photoLibraryService.convert(album: libraryAlbum)
                }.asDriver(onErrorJustReturn: []).startWith([]).distinctUntilChanged()

然后我将 assetDriver 映射到驱动我的集合视图的 dataSourceDriver。

我可以对 assetDriver 进行哪些更改以使其等待 isGridViewScrolling 变为 false？谢谢。

Answer 1

听起来你需要我的 stallUnless(_:initial:) 接线员。 https://gist.github.com/danielt1263/2b624d7c925d8b7910ef2f1e5afe177b


    /**
     Emits values immediately if the boundary sequence last emitted true, otherwise collects elements from the source sequence until the boundary sequence emits true then emits the collected elements.
     - parameter boundary: Triggering event sequence.
     - parameter initial: The initial value of the boundary
     - returns: An Observable sequence.
     */
    func stallUnless<O>(_ boundary: O, initial: Bool) -> Observable<Element> where O: ObservableType, O.Element == Bool {
        return Observable.merge(self.map(Action.value), boundary.startWith(initial).distinctUntilChanged().materialize().map(Action.trigger).takeUntil(self.takeLast(1)))
            .scan((buffer: [Element](), trigger: initial, out: [Element]()), accumulator: { current, new in
                switch new {
                case .value(let value):
                    return current.trigger ? (buffer: [], trigger: current.trigger, out: [value]) : (buffer: current.buffer + [value], trigger: current.trigger, out: [])
                case .trigger(.next(let trigger)):
                    return trigger ? (buffer: [], trigger: trigger, out: current.buffer) : (buffer: current.buffer, trigger: trigger, out: [])
                case .trigger(.completed):
                    return (buffer: [], trigger: true, out: current.buffer)
                case .trigger(.error(let error)):
                    throw error
                }
            })
            .flatMap { [=10=].out.isEmpty ? Observable.empty() : Observable.from([=10=].out) }
    }
}

Answer 2

您可以使用 combineLatest:

    let assetDriver = Driver
        .combineLatest(
            photoLibraryService.albumDriver,
            isGridViewScrolling
        )
        .filter { ! }
        .map { [=10=].0 }
        .flatMapLatest { libraryAlbum -> Driver<[LibraryAsset]> in
            photoLibraryService.convert(album: libraryAlbum)
                .asDriver(onErrorJustReturn: [])
        }
        .startWith([])
        .distinctUntilChanged()

如何在条件变为真之前限制可观察的

How to throttle observable until a condition becomes true

system.reactive

ios

swift

rx-swift

rx-cocoa