With the awesome announcement of Swift last week, alongside all of the other incredible announcements, I’m sure that your reaction was similar to mine: Where do I begin?!

I’ve been reading the book, watching the sessions, checking out the sample code, and basically trying to orient myself with the new syntax as much as possible.

One question I had today while listening to the latest episode of the Debug podcast was, “How will Grand Central Dispatch (GCD) work in Swift? Will GCD work in Swift?” With that question in mind I settled in, opened Xcode, and chose File > New > Project…

I chose a Single View Application since I wouldn’t need much of app to answer my question. I named it SwiftlyGCD and chose Swift as the language. I opened ViewController.swift and started typing out dispatch to see what would code-complete. Happily all of the wonderful GCD methods that we know and love appeared in the code-completion list in their Swift-equivalent notation.

For instance, dispatch_async() in Objective-C looks like so:

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void dispatch_async(dispatch_queue_t queue, dispatch_block_t block);

Whereas in Swift it appears like this:

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func dispatch_async(queue: dispatch_queue_t!, block: dispatch_block_t!)

As you can see we get a one for one translation from C to Swift thanks to Xcode 6. Additionally we get some extra niceties like named parameters. What does the code look like in usage?

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  dispatch_async(dispatch_get_main_queue(), {
      println("Currently dispatched asynchronously")
      })

The call to dispatch_get_main_queue() is exactly the same as we’re used to, while the block syntax is simplified to just a pair of {}.

Bottom line: GCD is fully available in Swift and works exactly as we’d expect. Way to go Apple!

UPDATES

After this post went live on Twitter Jacob Gorban replied and said, “It should even work with trailing block, no?”

He’s right! You can write the above dispatch like so:

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  dispatch_async(dispatch_get_main_queue()) {
      println("Currently dispatched asynchronously")
      }