RXSwift + UITableView with animated Cell ends up in flashing reloads - ios

Question

I have the following issue. I use RxSwift to bind my datasource to an UITableView like this:
self.presenter.posts
.bind(to: self.tableView.rx.items(cellIdentifier: "ListPostsCell")) { index, model, cell in
if let cell = cell as? ImagePostTableViewCell {
cell.viewModel = model
cell.actionButton.rx.action = self.action(for: model.postId, index: index)
}
}.disposed(by: self.bag)
When the tableview reaches the end of the datasource count I request more data and update the datasource (infinite scroll) like this:
self.tableView.rx.willDisplayCell
.map { $0.indexPath.item }
.distinctUntilChanged()
.withLatestFrom(self.presenter.posts) { (item, posts) -> Bool in
return item == posts.count - 3
}
.filter { $0 }
.withLatestFrom(self.presenter.posts)
.map { UsersPosts.Request(after: $0.last?.postId) }
.bind(to: self.usersPostsInteractor.receiveUsersPosts.inputs)
.disposed(by: self.bag)
This works fine and I can scroll infinite as expected. The problem is within my Cell:
class ImagePostTableViewCell: UITableViewCell {
#IBOutlet weak var postImageView: UIImageView!
#IBOutlet weak var haiScoreLabel: UILabel!
#IBOutlet weak var lastVoteLabel: UILabel!
#IBOutlet weak var actionButton: UIButton!
#IBOutlet weak var activtiyIndicator: UIActivityIndicatorView!
var bag: DisposeBag?
var viewModel: ImagePostTableViewCellViewModel? {
didSet {
let bag = DisposeBag()
guard let vm = viewModel else { return }
vm.image.asDriver(onErrorJustReturn: UIImage())
.drive(onNext: { image in
self.updateAppearanceFor(image)
}).disposed(by: bag)
self.haiScoreLabel.text = vm.haiScoreText
self.lastVoteLabel.text = vm.lastVoteText
self.actionButton.setTitle(vm.actionLabelText, for: .normal)
self.activtiyIndicator.startAnimating()
self.bag = bag
}
}
func updateAppearanceFor(_ image: UIImage?, animated: Bool = true) {
DispatchQueue.main.async {
if animated {
UIView.animate(withDuration: 0.5) {
self.displayImage(image)
}
} else {
self.displayImage(image)
}
}
}
private func displayImage(_ image: UIImage?) {
if let image = image {
self.show(image: image)
} else {
self.hide()
}
}
private func show(image: UIImage) {
self.postImageView.image = image
self.postImageView.alpha = 1.0
self.haiScoreLabel.alpha = 1.0
self.lastVoteLabel.alpha = 1.0
self.activtiyIndicator.stopAnimating()
}
private func hide() {
self.postImageView.image = nil
self.postImageView.alpha = 0
self.haiScoreLabel.alpha = 0
self.lastVoteLabel.alpha = 0
self.activtiyIndicator.startAnimating()
}
override public func prepareForReuse() {
super.prepareForReuse()
self.displayImage(.none)
self.viewModel = nil
self.bag = nil
}
}
As you can see there is an animation which ends up in an super smooth scrolling behaviour - but because of the datasource update, with every reload the animation starts and unchanged content flashes because of the animation.
In the end I want to avoid the reload for the visible cell but I really desperate here.
Any hints to follow? Thanks in advance!!!