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This tutorial walks through Grand Central Dispatch (GCD) in a carefully structured progression:

🥚 Foundations

1. 01 — Why GCD Exists
2. 02 — Thread vs Queue
3. 03 — Queue
4. 04 — Sync vs Async
5. 05 — Main Queue and Global Queues

🧑‍🍽️ Core Concepts

6. 06 — Quality of Service
7. 07 — DispatchWorkItem
8. 08 — Deadlocks
9. 09 — Delaying Work

⚡ Coordination

10. 10 — DispatchGroup
11. 11 — DispatchSemaphore
12. 12 — Barriers
13. 13 — Target Queues

🔒 Safety & Data Flow

14. 14 — Data Races and Thread Safety
15. 15 — Locks
16. 16 — The Thread Explosion Problem

🧠 Advanced Control

17. 17 — concurrentPerform
18. 18 — DispatchSource
19. 19 — Cancellation in GCD

🌊 Real-World Patterns

20. 20 — Callback Chains and Callback Hell
21. 21 — Common GCD Gotchas

🎓 Wrap-up

22. 22 — How Everything Fits Together
23. 23 — From GCD to Swift Concurrency

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By following this path, you'll go from:

👉 "GCD is a pile of confusing APIs 😵" to 👉 "I understand the mechanics async/await is built on 💡"

This is a companion series to SwiftConcurrencyExplained — read this one first for the low-level foundation, then that one for the modern high-level model.