Unexpected Crashes in iOS 17 with Combine and SwiftUI on ViewModel Binding
I'm upgrading from an older version and I've looked through the documentation and I'm still confused about I've searched everywhere and can't find a clear answer... I've searched everywhere and can't find a clear answer. I am experiencing unexpected crashes in my SwiftUI app when using Combine to manage state in my ViewModel. The app uses iOS 17 and SwiftUI for the UI, but occasionally, when the network response comes back, the app crashes with a "Unexpectedly found nil while unwrapping an Optional value" behavior. I've set up my ViewModel to publish changes, but it seems like the view is trying to access properties that haven't been updated yet. Here's a simplified version of my ViewModel: ```swift import Combine import SwiftUI class MyViewModel: ObservableObject { @Published var data: String? private var cancellables = Set<AnyCancellable>() func fetchData() { URLSession.shared.dataTaskPublisher(for: URL(string: "https://api.example.com/data")!) .map { $0.data } .decode(type: String.self, decoder: JSONDecoder()) .replaceError(with: nil) .receive(on: DispatchQueue.main) .assign(to: &$data) } } ``` In my SwiftUI view, I have: ```swift struct ContentView: View { @StateObject var viewModel = MyViewModel() var body: some View { VStack { if let data = viewModel.data { Text(data) } else { Text("Loading...") } } .onAppear { viewModel.fetchData() } } } ``` I've tried adding optional binding to avoid the crash, but it still occurs under certain conditions. Specifically, it seems to happen when there’s a delay in the network response. I also checked for retain cycles, and the `@StateObject` seems to be correctly managed. Could this be related to thread safety or timing issues, or is there something else I'm missing in my Combine chain? Any insights would be greatly appreciated! Is there a better approach? This is part of a larger API I'm building. I'd really appreciate any guidance on this. My development environment is Windows 10. Thanks for taking the time to read this! I'm on Ubuntu 22.04 using the latest version of Swift. What's the best practice here? This is happening in both development and production on CentOS. Any feedback is welcome!