Is there a way to force reloadData on a UICollectionView using RxSwift? - rx-swift

Question

I have a UICollectionView bound to an array of entities using BehaviorSubject and all is fine, data is loaded from the network and displayed correctly.
The problem is, based on user action, I'd like to change the CellType used by the UICollectionView and force the collection to re-create all cells, how do I do that?
My bind code looks like:
self.dataSource.bind(to: self.collectionView!.rx.items) {
view, row, data in
let indexPath = IndexPath(row: row, section: 0)
var ret: UICollectionViewCell? = nil
if (self.currentReuseIdentifier == reuseIdentifierA) {
// Dequeue cell type A and bind it to model
ret = cell
} else {
// Dequeue cell type B and bind it to model
ret = cell
}
return ret!
}.disposed(by: disposeBag)

Answer 1

The general way to solve problems in Rx is to think of what you want the output effect to be and what input effects can affect it.
In your case, the output effect is the display of the table view. You have identified two input effects "data is loaded from the network" and "user action". In order to make your observable chain work properly, you will have to combine your two input effects in some way to get the behavior you want. I can't say how that combination should take place without more information, but here is an article explaining most of the combining operators available: https://medium.com/#danielt1263/recipes-for-combining-observables-in-rxswift-ec4f8157265f

Answer 2

As a workaround, you can emit an empty list then an actual data to force the collectionView to reload like so:
dataSource.onNext([])
dataSource.onNext([1,2,3])

Answer 3

I think you can use different data type to create cell
import Foundation
import RxDataSources
enum SettingsSection {
case setting(title: String, items: [SettingsSectionItem])
}
enum SettingsSectionItem {
case bannerItem(viewModel: SettingSwitchCellViewModel)
case nightModeItem(viewModel: SettingSwitchCellViewModel)
case themeItem(viewModel: SettingCellViewModel)
case languageItem(viewModel: SettingCellViewModel)
case contactsItem(viewModel: SettingCellViewModel)
case removeCacheItem(viewModel: SettingCellViewModel)
case acknowledgementsItem(viewModel: SettingCellViewModel)
case whatsNewItem(viewModel: SettingCellViewModel)
case logoutItem(viewModel: SettingCellViewModel)
}
extension SettingsSection: SectionModelType {
typealias Item = SettingsSectionItem
var title: String {
switch self {
case .setting(let title, _): return title
}
}
var items: [SettingsSectionItem] {
switch self {
case .setting(_, let items): return items.map {$0}
}
}
init(original: SettingsSection, items: [Item]) {
switch original {
case .setting(let title, let items): self = .setting(title: title, items: items)
}
}
}
let dataSource = RxTableViewSectionedReloadDataSource<SettingsSection>(configureCell: { dataSource, tableView, indexPath, item in
switch item {
case .bannerItem(let viewModel),
.nightModeItem(let viewModel):
let cell = (tableView.dequeueReusableCell(withIdentifier: switchReuseIdentifier, for: indexPath) as? SettingSwitchCell)!
cell.bind(to: viewModel)
return cell
case .themeItem(let viewModel),
.languageItem(let viewModel),
.contactsItem(let viewModel),
.removeCacheItem(let viewModel),
.acknowledgementsItem(let viewModel),
.whatsNewItem(let viewModel),
.logoutItem(let viewModel):
let cell = (tableView.dequeueReusableCell(withIdentifier: reuseIdentifier, for: indexPath) as? SettingCell)!
cell.bind(to: viewModel)
return cell
}
}, titleForHeaderInSection: { dataSource, index in
let section = dataSource[index]
return section.title
})
output.items.asObservable()
.bind(to: tableView.rx.items(dataSource: dataSource))
.disposed(by: rx.disposeBag)
RxDataSources
swiftHub