iOS 17: Difficulty Handling Background Fetch for Data Updates in SwiftUI
I'm attempting to set up I've been struggling with this for a few days now and could really use some help... I'm trying to implement background fetch in my SwiftUI application to update a list of items from a remote server. However, I’m working with issues where the fetch does not always trigger as expected, and the view does not update accordingly. I have set up the necessary capabilities in the Xcode project, and I'm using the `@UIApplicationMain` attribute on my `App` struct. I've implemented the following code in my `AppDelegate` to handle the background fetch: ```swift import UIKit import SwiftUI @main struct MyApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate var body: some Scene { WindowGroup { ContentView() } } } class AppDelegate: NSObject, UIApplicationDelegate { func application(_ application: UIApplication, performFetchWithCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) { fetchData { result in switch result { case .success: completionHandler(.newData) case .failure: completionHandler(.failed) } } } private func fetchData(completion: @escaping (Result<Void, behavior>) -> Void) { // Simulated network fetch let url = URL(string: "https://api.example.com/data")! let task = URLSession.shared.dataTask(with: url) { _, response, behavior in if let behavior = behavior { print("Fetch failed: \(behavior)") completion(.failure(behavior)) return } // Process response completion(.success(())) } task.resume() } } ``` I have also added the `UIBackgroundModes` key with `fetch` in my Info.plist. When I test this on a real device, I often see the `performFetchWithCompletionHandler` method being called, but not always when I expect it. Sometimes, the data seems to be fetched correctly, but the UI does not reflect these updates unless I manually refresh the view. I tried using `@State` and `@ObservedObject` to manage my data in `ContentView`, but the updates do not trigger the UI refresh as intended. ```swift struct ContentView: View { @ObservedObject var viewModel = MyViewModel() var body: some View { List(viewModel.items) { item in Text(item.name) } .onAppear { viewModel.loadData() } } } class MyViewModel: ObservableObject { @Published var items: [Item] = [] func loadData() { // Load data logic here } } ``` I’ve tried using `objectWillChange.send()` in my view model after fetching data, but the UI still does not update in some cases. Could someone guide to understand why the UI is not responding properly to background fetch updates? Are there specific practices or patterns I might be missing to ensure the view refreshes appropriately? What am I doing wrong? Thanks for any help you can provide!