Does Swift support multi-threading and concurrency?

Yes, Swift supports multi-threading and concurrency. It provides several features and frameworks that allow developers to write concurrent code and work with multiple threads.

Grand Central Dispatch (GCD)

One of the key frameworks for achieving concurrency in Swift is Grand Central Dispatch (GCD). GCD is a powerful tool for managing concurrent tasks. It uses a thread pool model and provides a simple and efficient way to perform tasks asynchronously.

With GCD, you can create dispatch queues, which are responsible for executing tasks in parallel. There are two types of dispatch queues:

1. Serial Dispatch Queue: Executes tasks one at a time in the order they are added.
2. Concurrent Dispatch Queue: Executes tasks concurrently and does not guarantee the order of execution.

GCD also provides dispatch groups, which allow you to group multiple tasks and wait for them to complete. This is useful for coordinating multiple concurrent tasks.

Async/Await Syntax

Starting from Swift 5.5, you can also use the async/await syntax, which simplifies asynchronous programming. Async/await allows you to write asynchronous code in a more sequential and readable manner.

By marking a function with the async keyword, you can make it asynchronous. Within the function, you can use the await keyword to suspend the execution until a particular asynchronous task completes.

Swift also provides other features and constructs like Operation and DispatchSemaphore for fine-grained control over multi-threading and concurrency.