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Wrap up

Although I've tried to simplify things as much as possible, GCD still isn't easy. That said, it's much easier than the alternatives: GCD automatically handles thread creation and management, automatically balances based on available system resources, and automatically factors in Quality of Service to ensure your code runs as efficiently as possible. The alternative is doing all that yourself!

There's a lot more we could cover (not least how to create your own queues!) but really you have more than enough to be going on with, and certainly more than enough to complete the rest of this series. We'll be using GCD again, so it might help to keep this reference close to hand!

Review what you learned

Anyone can sit through a tutorial, but it takes actual work to remember what was taught. It’s my job to make sure you take as much from these tutorials as possible, so I’ve prepared a short review to help you check your learning.

Click here to review what you learned in project 9.

Challenge

One of the best ways to learn is to write your own code as often as possible, so here are three ways you should try your new knowledge to make sure you fully understand what’s going on:

  1. Modify project 1 so that loading the list of NSSL images from our bundle happens in the background. Make sure you call reloadData() on the table view once loading has finished!
  2. Modify project 8 so that loading and parsing a level takes place in the background. Once you’re done, make sure you update the UI on the main thread!
  3. Modify project 9 so that your filtering code takes place in the background. This filtering code was added in one of the challenges for project 9, so hopefully you didn’t skip it!

Share your success!

One of the most effective motivators of success is sharing your progress with other people – when you tell folks what you're doing and what you've learned, it encourages you to come back for more, which in turn will help you reach your app development goals faster.

So, now that you've done all the hard work it's time to share your success: tell folks that you've completed this project, either by clicking the button below to start composing a tweet, or by writing your own message from scratch. This will definitely encourage you to keep learning, but it will also help other folks discover my work – thank you!

 

About the author

Paul Hudson is the creator of Hacking with Swift, the most comprehensive series of Swift books in the world. He's also the editor of Swift Developer News, the maintainer of the Swift Knowledge Base, and Mario Kart world champion. OK, so that last part isn't true. If you're curious you can learn more here.

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