Alan iOS Concurrency - Understanding Dispatch Queues and Operation Queues

🙋🏻‍♂️ Self-diagnosis chart

After class, you will have a clear understanding and understanding of the concepts below.

• I have a clear understanding of the concept of dispatch queues . (Yes/No)
• I understand the types of dispatch queues and quality of service (QoS). (Yes/No)
• In most cases, I know why I shouldn't use the Sync method, and I understand the difference between when I absolutely must use the Sync method . (Yes/No)
• I know about the concept of dispatch groups . (Yes/No)
• I know what to watch out for when handling asynchronous functions in a dispatch group . (Yes/No)
• I understand the concept of dispatch work items and why they are used. ( Yes/No)
• I know the concept of dispatch semaphores and how to use them. (Yes/No)
• When designing objects, you should clearly understand the considerations for the possibility of multiple threads accessing them, and design the right objects . (Yes/No)
• When creating a project of the table view/collection view type that downloads images, I am clear about the points to be careful about in handling the asynchrony concept . (Yes/No)
• I have a clear understanding of potential issues that can arise when using dispatch queues (when multiple threads access data), especially race conditions , and I know how to use TSan (Thread Sanitizer Tool) . (Yes/No)
• I have a clear understanding of how to write thread-safe code . (Yes/No)
• I know the concept of extended operations in dispatch queues and the differences between them. (Yes/No)
• You can use it to distinguish when to use an operation queue instead of a dispatch queue. (Yes/No)
• I understand the code for asynchronous operations (AsyncOperation) , which can handle asynchronous functions. (Yes/No)
• You can freely use the main functions of the operation (setting the order of tasks, canceling them) . (Yes/No)

📝 Lecture Table of Contents

(It is largely divided into GCD and Operation parts. Even if you have a good understanding of GCD, you may be unfamiliar with Operation (task class) , a concept developed from GCD. It is structured so that you can understand everything in one lecture, more clearly and easily than any blog or lecture.)

🖼️ Example of picture caption style

(Examples of various illustration and diagram explanation methods used in class.)

🌈 Materials provided in the lecture 

Various materials are provided below.

1. GCD Summary PDF - Chapter 287
2. Operation-related Summary PDF - Chapter 89
3. Code for GCD related explanation (playground file) - 19 pages (excluding source files)
4. Code for Operation-related explanations (playground files) - 8 pages (excluding source files)
5. iOS project files - 8
6. Interpretation of the reference articles (2)

(All materials in the folder above are provided.)

🙌 Reference materials used in the production of the lecture

Although I referenced the materials below, I designed all the illustration descriptions myself.

1. Video lecture ( iOS Concurrency with GCD and Operations ) - Raywenderlich https://www.raywenderlich.com/3648-ios-concurrency-with-gcd-and-operations
2. Book ( Concurrency by Tutorials ) - Raywenderlich https://store.raywenderlich.com/products/concurrency-by-tutorials
3. Article ( Operation and OperationQueue Tutorial in Swift ) - Raywenderlich https://www.raywenderlich.com/5293-operation-and-operationqueue-tutorial-in-swift
4. Article ( The thread safety of lazy variables in Swift ) https://medium.com/what-i-talk-about-when-i-talk-about-ios-developmen/the-thread-safety-of-lazy-variables-in-swift-b20184ef5a38

🙋🏻‍♂️ Is the lecture content very different from the <Lecture Production Reference Materials>?

There really is a lot of difference.

If I had simply attempted to create a translation-level lecture based solely on the reference materials above, I would not have planned this lecture. I have chosen the best possible method of explanation, personally creating PPTs with efficient and effective explanations, direct illustrations, and diagrams on these topics to help you intuitively understand how threads actually work . As I mentioned above , I have reviewed the reference materials more than ten times, and while covering all the content, this lecture aims to make the explanations much easier and the various illustrations make for an intuitive understanding.

And since the content of these figures is something I personally organized over a period of more than two full-time months, I don't think you'll find an explanation like this or this detailed anywhere else (including overseas materials). For example, if there was a single line in the reference material (raywenderlich's video lecture) that said, "This problem can also occur with lazy var," I would have personally identified all the issues related to lazy var, organized them, and presented solutions while helping with intuitive understanding with figures.

Understanding the big picture makes writing code much easier. I've tried to maintain a balance between understanding through pictures and applying code as much as possible, which makes this book stand out from other reference materials. Compared to reference materials, this book offers much more detail, intuitiveness, and richer material, along with consistent, easy-to-understand explanations.

🐠 About the code provided

To help you understand the topic, code files are provided and it is also covered in the class . Most of the code provided is adopted from the GCD video lectures by raywenderlich within the scope permitted by the license ( the adopted parts are specified ). For the parts where the license does not permit (the code provided in the raywenderlich book), I wrote the code myself, and in the main framework , I tried to ensure the reliability of the code provided by writing similarly.

Additionally, to help you understand the code we provide, we've rearranged the code order and added more code for more detailed explanations, providing a variety of examples to help you understand the content of this course.

🤔 About class pricing

You might be surprised by the high price for a single topic, but I assure you, the extensive content is worth the price . To explain this content, I've personally created a PDF document, which includes 287 GCD-related pages and 89 Operation-related pages, totaling 376 pages . (The actual material I use in my video lectures consists of approximately 830 PPT pages, excluding code.)

This course covers virtually everything you can find in international resources related to GCD/Operations , and most of the figures and diagrams in this course are my own . A significant amount of time and effort went into this course, and I believe it's a crucial topic for future developer development. Therefore, from my personal perspective, I planned and created this course based on the principles of "I wish there were more resources and lectures like this ."

Personally, I believe that paying for a course is a trade-off between time and money . I believe it will be worth the money, saving you time studying the subject . I hope you'll save time and gain greater satisfaction. I will strive to provide you with quality content that exceeds your price, and I sincerely ask you to keep this in mind. ^^

💌 Lecture content license related

In the cases where I've even slightly referenced images or other materials in this lecture, the relevant URL address is provided in the PDF . Except for those cases, all materials are my own. Therefore, if you're organizing the lecture's explanations on a blog or other site, I kindly ask you to include the link to this lecture .

However, it is prohibited under any circumstances to post the entire contents of this lecture on a blog or to share the PDF files used as lecture materials .

👀 Preview of lecture content provided

Before you decide to take a class, we've made it possible for you to check out the lecture style in advance.

• ( A preview of about an hour related to Section 0.1.GCD/Operation)
• ( A 5-minute preview related to Section 10. 1. Operation)

You can take a look at the lectures that are provided in preview and decide whether to take them :)