https://stackoverflow.com/questions/58177116/c-sharp-fire-async-from-loop

async Task Start()
{
    //Method 1: fire all async event, then wait for all async task are completed
    //before handling all the results non asyncally

    List<Task<int>> FiredTasks = new List<Task<int>>();
    for (int i = 0; i< 6; i++)
    { 
        Debug.Log("async task firing "+i);
        Tasks.Add(DoAsyncTask("someStringValue", i));
    }

    foreach (int item in await Task.WhenAll(FiredTasks))
    {
        Debug.Log("async task ended, returned result: " + item);
        //add code to handle the returned result here.
    }

    //Method 2, fire all async event, then handle each result as they complete without waiting for others
    List<Task<int>> FiredTasks = new List<Task<int>>();
    for (int i = 0; i < 6; i++)
    {
        Debug.Log("Firing async event "+i);
        Tasks.Add(DoAsyncTask("someStringValue", i));
    }

    //If I understnd correctly, this loop basically tells each of the fired async task what to do when they are done.
    foreach (Task<int> task in FiredTasks)
    {
        await HandleAsyncResult(task);
    }
}

async Task<int> DoAsyncTask(string name, int index)
{
    await Task.Delay(6000);
    // or you can do add some randome delay in here so you can see the individual task completing at different time
    await Task.Delay(UnityEngine.Random.Range(1,10) * 1000);
    return index;
}

async Task HandleAsyncResult(Task<int> task)
{
    int taskResult = await task;
    Debug.Log("Done " + taskResult);
}