Starting with C# 8.0, you can create and consume streams asynchronously. A method that returns an asynchronous stream has three properties:
- It's declared with the
- It returns an IAsyncEnumerable<T>.
- The method contains
yield return statements to return successive elements in the asynchronous stream.
Consuming an asynchronous stream requires you to add the
await keyword before the
foreach keyword when you enumerate the elements of the stream. Adding the
await keyword requires the method that enumerates the asynchronous stream to be declared with the
async modifier and to return a type allowed for an
async method. Typically that means returning a Task or Task<TResult>. It can also be a ValueTask or ValueTask<TResult>. A method can both consume and produce an asynchronous stream, which means it would return an IAsyncEnumerable<T>. The following code generates a sequence from 0 to 19, waiting 100 ms between generating each number:
public static async System.Collections.Generic.IAsyncEnumerable<int> GenerateSequence()
for (int i = 0; i < 20; i++)
yield return i;