Give me an example of how async await

In Swift, the async and await keywords are used to handle asynchronous operations. When a function is marked with the async keyword, it indicates that the function may suspend its execution to wait for an asynchronous operation to complete. The await keyword is used when calling an async function to indicate that the function may pause at that point until the operation is finished.

For example, in the session titled "A Swift Tour: Explore Swift’s features and design," it is explained that when an async function is called, the await keyword is used to indicate a potential suspension point. This allows the CPU to be yielded to other tasks that have work to do while waiting for the asynchronous operation to complete. This is particularly useful in server development environments where tasks like reading from the disk or messaging another service are common.

Additionally, in the session "Explore Swift performance," it is discussed how async functions are implemented. They keep their local state on a separate stack from the C stack and are split into multiple functions at runtime to handle potential suspension points efficiently.

For more detailed information, you can refer to the session A Swift Tour: Explore Swift’s features and design (19:10) and Explore Swift performance (24:54).