OperationQueue.main vs DispatchQueue.main

ios swift grand-central-dispatch nsoperationqueue ui-thread
AppsDev picture AppsDev · Nov 23, 2016 · Viewed 15.4k times · Source

When you need to perform something on the main thread in the completion block of a networking task or an operation, which of these ways to get it would be the most appropriate and why?:

  • OperationQueue.main.addOperation
  • DispatchQueue.main.async

Answer

MrMage picture MrMage · Nov 23, 2016

For details on the differences between the two types of queue, see Lion's answer.

Both approaches will work. However, NSOperation is mostly needed when more advanced scheduling (including dependencies, canceling, etc.) is required. So in this case, a simple

DispatchQueue.main.async { /* do work */ }

will be just fine. That would be equivalent to

dispatch_async(dispatch_get_main_queue(), ^{ /* do work */ });

in Objective-C, which is also how I would do it in that language.

Related questions

Waiting for multiple asynchronous download tasks

I want to download some files, for example 100 files, at the same time. So I decided to add my download threads to a dispatch queue, and GCD will adjust how many threads will run at the same time. The problem …

Read More
When to use Semaphore instead of Dispatch Group?

I would assume that I am aware of how to work with DispatchGroup, for understanding the issue, I've tried: class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() performUsingGroup() } func performUsingGroup() { let dq1 = DispatchQueue.global(qos: .userInitiated) let dq2 = DispatchQueue.global(…

Read More
Wait for completion handler to finish - Swift

I am trying to check if UserNotifications are enabled and if not I want to throw an alert. So I have a function checkAvailability which checks multiple things, including the UserNotification authorization status. func checkAvailabilty() -> Bool { // // other checking // …

Read More