Debugging a Legacy Dependency Injection Issue in a Swift Staging Environment
I'm wondering if anyone has experience with Currently developing a feature that involves a legacy codebase which uses a custom dependency injection framework... While running tests in the staging environment, I’ve noticed that certain services are not being instantiated correctly, leading to `nil` values where non-optional instances are expected. In particular, the `UserService` is supposed to be injected into the `ProfileViewModel`, but it seems to be failing silently. Here’s how I’m trying to set things up: ```swift class AppDelegate: UIResponder, UIApplicationDelegate { var window: UIWindow? let container = DIContainer() // Custom DI container func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool { container.register(UserService.self) { _ in UserServiceImpl() } // Implementation let profileViewModel = container.resolve(ProfileViewModel.self) // Setting up the ProfileView with ViewModel return true } } ``` The registration seems fine, but when I check the `ProfileViewModel`, it’s always getting a `nil` value for `userService`. I’ve tried adding debug statements in the `resolve` function within my DI framework: ```swift func resolve<T>(_ type: T.Type) -> T? { print("Resolving type: \(type)") // ... Implementation } ``` This is showing that it’s attempting to resolve the type, but it never reaches the point where the service is actually instantiated. I also checked for circular dependencies - none exist in this case. Could there be an issue with the lifecycle of the injected services? I've come across suggestions that maybe the container’s scope is limited to the AppDelegate. Should I be using a shared instance or singleton for the container? Any guidance or best practices on managing service lifecycles in a staging environment for legacy Swift code would be greatly appreciated. This is part of a larger microservice I'm building. Any suggestions would be helpful.