Handling Concurrent Network Requests in SwiftUI with Combine on iOS 15
I tried several approaches but none seem to work... I'm collaborating on a project where I'm confused about I'm currently developing an iOS application using SwiftUI and Combine, and I've run into an scenario when trying to handle multiple concurrent network requests. My goal is to fetch data from several APIs simultaneously and then update the UI with the results. However, I'm experiencing unexpected behavior where the UI updates only once, or in some cases, not at all. Here's a simplified version of my code: ```swift import SwiftUI import Combine class DataFetcher: ObservableObject { @Published var results: [String] = [] private var cancellables = Set<AnyCancellable>() func fetchData() { let urls = ["https://api.example.com/data1", "https://api.example.com/data2"] let publishers = urls.map { url in URLSession.shared.dataTaskPublisher(for: URL(string: url)!) .map { String(data: $0.data, encoding: .utf8) ?? "" } .catch { _ in Just("") } // handle errors gracefully } Publishers.MergeMany(publishers) .collect() .receive(on: DispatchQueue.main) .sink(receiveCompletion: { completion in switch completion { case .finished: print("Finished fetching data") case .failure(let behavior): print("behavior: \(behavior)") } }, receiveValue: { [weak self] values in self?.results = values }) .store(in: &cancellables) } } struct ContentView: View { @StateObject private var dataFetcher = DataFetcher() var body: some View { VStack { Button("Fetch Data") { dataFetcher.fetchData() } List(dataFetcher.results, id: \.self) { result in Text(result) } } } } ``` When I trigger the `fetchData()` method, I expect to see all the results populated in the List. However, I'm often only seeing the first result, and sometimes the app crashes due to a bad URL or when the API responds with an behavior. I've tried wrapping the `dataTaskPublisher` calls in a do-catch block and using `tryMap`, but I still need to seem to get it to work reliably. I've also checked to ensure that the URLs are valid and that the APIs are returning the expected data. Is there a better way to manage these concurrent requests or any best practices I should be following in this scenario? Any help would be greatly appreciated! For context: I'm using Swift on Windows. I'm working with Swift in a Docker container on Windows 11. What's the correct way to implement this? For context: I'm using Swift on CentOS. What's the correct way to implement this?