Reactive<UISegmentedControl> in UITableViewCell

Question

我试图从UITableView中添加删除单元格，具体取决于UISegmentedControl中的值变化，该值位于UITableViewCell的一个内部。

问题是存在一个循环依赖项，并且tableView一直在重新加载。我通过使用distinctUntilChanged避免了这种无限重加载，但有时还是会调用两次。

我的目标是根据段控件中的选择更改行数。

UITableViewCell中的代码

extension CardTableViewCell {

    /// This function is called every time in `cellForRowAtIndexPath` for the tableView.

    func bind(viewModel: TableViewViewModel?) {
        self.viewModel = viewModel
        if let viewModel = viewModel {
            segment.rx.selectedSegmentIndex
                .asDriver()
                .flatMap { Driver.just($0 == 0)}
                .distinctUntilChanged()
                .drive(onNext: { value in

                    print(">>>> VALUE CHANGED \(value)")
                    viewModel.reloadTableView()}

                // Here when I reload the table view this is called again and a cyclic dependency is created

                ) >>> disposeBag
        }
    }
}

控制台返回以下内容

⚠️ Reentrancy anomaly was detected.
  > Debugging: To debug this issue you can set a breakpoint in /Users/harshvishwakarma/Documents/GitHub/banking-app-ios/Pods/RxSwift/RxSwift/Rx.swift:97 and observe the call stack.
  > Problem: This behavior is breaking the observable sequence grammar. `next (error | completed)?`
    This behavior breaks the grammar because there is overlapping between sequence events.
    Observable sequence is trying to send an event before sending of previous event has finished.
  > Interpretation: This could mean that there is some kind of unexpected cyclic dependency in your code,
    or that the system is not behaving in the expected way.
  > Remedy: If this is the expected behavior this message can be suppressed by adding `.observeOn(MainScheduler.asyncInstance)`
    or by enqueing sequence events in some other way.

Answer 1

您将需要使用像[RxDataSources][1]这样的库，或者以其他方式编写您自己的数据源类。默认数据源的行为是在表视图上调用reloadData()，但是您需要一个按需追加/删除单元格，而不是总是加载整个tableView。

如果您觉得RxDataSources太重，那么您可以自己编写一个简单的数据源。下面是一个例子：https://github.com/danielt1263/RxMultiCounter/blob/master/RxMultiCounter/RxExtensions/RxSimpleAnimatableDataSource.swift