I have an ObservableObject which can do a CPU-bound heavy work: import Foundation import SwiftUI @MainActor final class Controller: ObservableObject { @Published private(set) var isComputing: Boo...

Currently, I have the following code class ShopViewController: UIViewController { @IBAction func buy(_ sender: Any) { Task { // Will run in main thread, because ShopViewController is // marke...

I would like to understand if it's needed to declare the Task itself as MainActor considering the following block of code. func login() { Task { [weak self] in let result = await self?.loginServi...

Okay so we all know that in traditional concurrency in Swift, if you are performing (for example) a network request inside a class, and in the completion of that request you reference a function th...

When creating a Task in a task-less context (e.g. from some random AppKit code), is there a difference between creating a detached or a regular task? For example, calling Task.detached or Task.ini...

I am trying to perform a series of network requests and would like to limit the number of concurrent tasks in the new Swift Concurrency system. With operation queues we would use maxConcurrentOpera...

I'm new (like most everyone, I suppose) to Swift concurrency, and I'm running into a compiler error I don't know what to do with. struct Thing { var counter = 0 mutating func increment() async {...

I am listening for changes of a publisher, then fetching some data asynchronously in my pipeline and updating the view with the result. However, I am unsure how to make this testable. How can I bes...

In WWDC 2021 video, Protect mutable state with Swift actors, they provide the following code snippet: actor ImageDownloader { private var cache: [URL: Image] = [:] func image(from url: URL) asyn...

I’m currently migrating my app to use the concurrency model in Swift. I want to serialize Tasks to make sure they are executed one after the other (no paralellism). In my use case, I want to listen...

Integrating actors with existing code doesn't really seem to be as simple as Apple wants you to believe. Consider the following simple actor: actor Foo { var value: Int = 0 } Trying to access thi...

Here is the code in Apple developer document。 let url = URL(string: "https://example.com")! @State private var message = "Loading..." var body: some View { Text(message) .tas...

Problem: I have the following function which shows a warning No calls to throwing functions occur within 'try' expression Questions: Why is this warning shown? (The code inside the task throws an ...

In this case the async function reads a file and returns the parsed contents. In my view I want to load the contents off of the main thread, and then update the view once complete. I've used this p...

I have a callback based API. func start(_ completion: @escaping () -> Void) I'd like to write an async/await wrapper on top of that API, deferring the implementation to original callback based ...

I have an existing debouncer utility using DispatchQueue. It accepts a closure and executes it before the time threshold is met. It can be used like this: let limiter = Debouncer(limit: 5) var valu...

I would like to have some sort of global variable that is synchronized using @MainActor. Here's an example struct: @MainActor struct Foo {} I'd like to have a global variable something like this: ...

I have a situation where I'm creating many Cocoa objects in a loop using async/await, and the memory spikes because the objects are only released when the loop is over (instead of every iteration)....

I need to use my own custom error enum in tasks that I create: enum MyError: Error { case someError } var myTask: Task<MyModel, MyError> = Task { () throws -> MyModel in // in case of a...

I try to check the actor's behavior. This is a new feature provided by Swift5.5. I've created a playground with an example code from the official documentation swift.org: import Foundation acto...

My intent is to understand the “cooperative thread pool” used by Swift 5.5’s async-await, and how task groups automatically constrain the degree of concurrency: Consider the following task group co...

I recently saw that Swift had introduced concurrency support with the Actor model in Swift 5.5. This model enables safe concurrent code to avoid data races when we have a shared, mutable state. I w...