iOS Concurrency with GCD and Operations - Part 12: | Ray Wenderlich

Review what you've learned in our video course iOS Concurrency with GCD & Operations, and get some hints and tips for handling concurrency in iOS.

This is a companion discussion topic for the original entry at

Links mentioned in this video:

This course has substantially increased my confidence with GCD and Operations, and makes me more comfortable now with the official docs too - thank you Audrey.

thank you!! I’m so glad you found it helpful :smile:

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You are a very good teacher. I like it that you have broken down the lessons in understandable chunks.

Too often in online courses, what is attempted to teach is buried inside a very complex program. I prefer small chunks building up to the more complex if increased complexity is included.

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Thank you Audrey and RW for making this course happen. It’s good to know somebody keeps the training ball rolling…

Apple still keeps their documentation in the Objective-C and their doc support for Swift 3 is not too swifty at all. (I’m one of those new guys who’ve learned iOS app dev in Swift only, and I’m really hoping to keep it that way if I can…)

Audrey, you are an admirable educator! You explain complex topics clearly, and to the point, and the code examples are awesome.

You made me a new RW subscriber! No regrets. :+1:

(Now how about a new tutorial on intermediate/advanced CloudKit and CoreData… which might include concurrency usage examples… ? Well it’s just an idea. :slight_smile:)

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thank you so much Mark! CloudKit and CoreData are also very essential topics, and I think you won’t be disappointed :wink:

This theme for me was a big black box, but now it’s not … at least for now so black :wink:
I liked how this course was laid out: size of the steps and playgrounds combined with XCode project.

So, Big Thank You, Audrey and RW team! :slight_smile:

thanks Ilmar! it was the same for me :wink: I learned so much while making this course!

Grand Central Dispatch Tutorial for Swift 3: Parts 1 & 2 have been updated for Swift 3 by Christine Abernathy. Link is to Part 1.

Fantastic tutorial series. Thank you so much Audrey. Very well done!!


Fantastic series. Thanks Audrey!

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Thanks Audrey. Really enjoyed all the videos. You have explained it very well. Thank you for your good effort.

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@robmontesinos @johnisaac @remyagiri.r Really glad you like it guys! Cheers! :]

Hey guys,

Could you update this tutorial in order to work with swift 5.2? most app examples don’t work with Xcode 11.x


hi Roberto! I’m currently working on updating this course.

Scott Grosch’s book is up to date for Swift 5.1.

Great tutorial @audrey, now I feel more comfortable thinking asynchronously :stuck_out_tongue:
Also, I noticed the first lecture talked about ‘locks’ but here only one approach was shown, ie using serial queues. (EDIT: Was talked of in Lec 11)
Also, I noticed a bool flag ‘semaphore’ being used to ensure thread safety, didn’t see how or its usage in this tutorial series, do consider introducing them in the revision of this course :smiley:

hi akashlal! I think the move is away from low-level tools, mainly because they’re much harder to use safely. The update will include DispatchSemaphore, but only to control the number of concurrent threads in a dispatch group.

Thanks for working through this course so thoroughly!

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@che1404 @akashlal Please check out the updated version of the course when you get a chance:

I hope it helps!