чем task отличается от GCD

In the context of Apple's WWDC sessions, a "task" in Swift is a fundamental unit of concurrency that represents an independent concurrent execution context. Tasks are lightweight and can be created in large numbers, allowing for concurrent execution of code. They can perform asynchronous operations and suspend to yield the CPU to other tasks while waiting for these operations to complete. This makes tasks suitable for handling concurrent operations efficiently.

On the other hand, Grand Central Dispatch (GCD) is a lower-level API for managing concurrent code execution on multicore hardware. It provides a way to execute code asynchronously by dispatching tasks to dispatch queues, which can be either serial or concurrent. GCD handles the scheduling of these tasks, optimizing for system performance and resource utilization.

The key difference is that Swift's concurrency model, which includes tasks, is more integrated into the language itself, providing a higher-level abstraction with features like async/await, actors, and structured concurrency. This model aims to simplify the management of concurrency and make it safer by providing guarantees about data-race safety and execution context.

For more details on Swift's concurrency model, you can refer to the session A Swift Tour: Explore Swift’s features and design (18:33).