NEW! Master Swift design patterns with my latest book! >>

How to run code on the main thread using GCD async()

Paul Hudson       @twostraws

Swift offers you two ways to run code on the main thread: GCD and performSelector(onMainThread:). The first option looks like this:

DispatchQueue.main.async { [unowned self] in
    self.yourCodeHere()
}

The second option looks like this:

performSelector(onMainThread: #selector(yourCodeHere), with: nil, waitUntilDone: false)

The GCD option (the first one) has the advantage that you can write your code inline, whereas the second one requires a dedicated method you can call.

Available from iOS 4.0 – see Hacking with Swift tutorial 9

Did this solution work for you? Please pass it on!

Other people are reading…

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.

Help support Hacking with Swift

This site is funded by Hacking with Swift supporters who buy my e-books. If you can, please support my work – it comes packed with bonus material!

MASTER SWIFT NOW
Buy Practical iOS 12 Buy Pro Swift Buy Swift Design Patterns Buy Practical iOS 11 Buy Swift Coding Challenges Buy Server-Side Swift (Vapor Edition) Buy Server-Side Swift (Kitura Edition) Buy Hacking with macOS Buy Advanced iOS Volume One Buy Hacking with watchOS Buy Hacking with tvOS Buy Hacking with Swift Buy Dive Into SpriteKit Buy Swift in Sixty Seconds Buy Objective-C for Swift Developers Buy Beyond Code

Was this page useful? Let me know!

Click here to visit the Hacking with Swift store >>