Best practices for managing asynchronous data fetching in SwiftUI for mobile compatibility
During development of a SwiftUI application targeting both iOS 15 and 16, I've been tasked with ensuring that our data fetching handles mobile performance optimally while maintaining a responsive UI. Previously, I implemented a basic asynchronous data fetch using `URLSession`, but faced issues with the UI freezing when loading extensive data sets, especially on older devices. Here’s a snippet of my initial approach: ```swift struct ContentView: View { @State private var data: [MyModel] = [] @State private var isLoading: Bool = false var body: some View { VStack { if isLoading { ProgressView() } else { List(data) { item in Text(item.name) } } } .onAppear(perform: loadData) } func loadData() { isLoading = true let url = URL(string: "https://api.example.com/data")! URLSession.shared.dataTask(with: url) { data, response, error in if let data = data, let decodedData = try? JSONDecoder().decode([MyModel].self, from: data) { DispatchQueue.main.async { self.data = decodedData self.isLoading = false } } else { // Handle error DispatchQueue.main.async { isLoading = false } } }.resume() } } ``` While this works, it doesn't feel optimal. After some research, I’m considering using `Combine` for more reactive data handling and avoiding blocking the main thread. Here’s my revised approach with `Combine`: ```swift import Combine class DataFetcher: ObservableObject { @Published var data: [MyModel] = [] private var cancellables = Set<AnyCancellable>() func fetchData() { let url = URL(string: "https://api.example.com/data")! URLSession.shared.dataTaskPublisher(for: url) .map { $0.data } .decode(type: [MyModel].self, decoder: JSONDecoder()) .replaceError(with: []) .receive(on: DispatchQueue.main) .assign(to: &$data) } } struct ContentView: View { @StateObject private var fetcher = DataFetcher() var body: some View { List(fetcher.data) { item in Text(item.name) } .onAppear { fetcher.fetchData() } } } ``` Implementing this change has not only streamlined the data fetching process, but also improved responsiveness across different devices. However, I’m curious about further optimization. Would using a caching mechanism with `NSCache` or integrating `ViewStore` from `The Composable Architecture` provide even more benefits when dealing with larger data sets? Any best practices or insights into potential pitfalls with this approach would be greatly appreciated. I'm open to any suggestions. Any help would be greatly appreciated!