using System;

using System.Threading.Tasks;

using System.Collections.Generic;

IAsyncEnumerable<int> numbers = GetNumbers();

await foreach (int n in numbers)

{

    Console.WriteLine($"取得 {n}");

}

​

async IAsyncEnumerable<int> GetNumbers()

{

    await Task.Delay(1000);

    yield return 1;

    await Task.Delay(1000);

    yield return 2;

    await Task.Delay(1000);

    yield return 3;

}

​

​