I have this "purple warning" on line 31, however my code only works without .receive(on: DispatchQueue.main) If I set .receive(on: DispatchQueue.main) or .receive(on: RunLoop.main), or simply run on DispatchQueue.main.async {} the publisher never fires. Any clues? Is it ok to keep it "purple" ? class ImageLoader: ObservableObject {   private var cancellable: AnyCancellable?   private var cache: ImageCache   @Published var image: UIImage?   private let url: URL   init(url: URL, cache: ImageCache) {     self.url = url     self.cache = cache   }   deinit {     cancellable?.cancel()   }   func load() {     if let image = cache[url] {       dispatchToMainThreadIfNeeded {         self.image = image       }       return     }     cancellable = URLSession.shared.dataTaskPublisher(for: url)       .map { UIImage(data: $0.data) }       .handleEvents(receiveOutput: { [weak self] in self?.cache($0) })       .replaceError(with: nil)       .sink { value in         self.image = value // Dispatch on main thread is not firing the publisher..     }   }   func cancel() {     cancellable?.cancel()   }   private func cache(_ image: UIImage?) {     image.map { cache[url] = $0 }   } } UDP what sort of work is .assign(to: \.image, on: self) instead of .sink { self.image = $0 }. Seems like only on device, not on Simulator..