Unexpected UI lag when using SwiftUI with Combine for network data updates
I'm trying to figure out After trying multiple solutions online, I still can't figure this out... I tried several approaches but none seem to work. I'm experiencing important UI lag in my SwiftUI application when using Combine to update a list of items fetched from a network request. I'm using SwiftUI 2.0 and Combine 1.0, and the scenario seems to occur particularly when the data updates frequently. My view is a simple list that displays data fetched from a REST API. Here's a snippet of the relevant code: ```swift struct ContentView: View { @StateObject private var viewModel = ItemViewModel() var body: some View { List(viewModel.items) { item in Text(item.name) } .onAppear { viewModel.fetchItems() } } } class ItemViewModel: ObservableObject { @Published var items: [Item] = [] func fetchItems() { let url = URL(string: "https://api.example.com/items")! URLSession.shared.dataTaskPublisher(for: url) .map { $0.data } .decode(type: [Item].self, decoder: JSONDecoder()) .replaceError(with: []) .receive(on: DispatchQueue.main) .assign(to: &$items) } } ``` I've tried moving the network call to a background thread using `subscribe(on: DispatchQueue.global())`, but the UI still lags when new data is received. I've also noticed that the lag is more pronounced when the number of items grows larger. The behavior messages in the console are minimal, but I did see a few complaints about main thread performance when heavy updates occur. Is there a more efficient way to handle frequent updates in SwiftUI with Combine? Should I consider batch updates or some form of throttling, or is there a different approach that might improve performance? Any best practices for this scenario would be appreciated! My development environment is Ubuntu. Am I missing something obvious? I'm working on a CLI tool that needs to handle this. Has anyone else encountered this? The project is a CLI tool built with Swift.