AsyncEvent_Sample.cs

AsyncEvent_Sample.cs

/**
    CancellationTokenSource eventActCts;

    void Cancel_AsynEventTest()
    {
        if(eventActCts != null)
        {
            eventActCts.Cancel();
        }
        eventActCts = null;
    }

    async Task AsyncEventTest()
    {
        try
        {
            eventActCts = new CancellationTokenSource();

            float v = await asyncEvent_Test.AsyncEventAct(eventActCts.Token);
            Debug.LogWarning("Result");
            Debug.LogWarning(v);
        }
        catch (OperationCanceledException ex)
        {
            Debug.LogWarning($"OperationCanceledException: {ex}");
        }
    }
**/

using System.Collections;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;
using UnityEngine;

public class AsyncEvent_Sample : MonoBehaviour
{
    public delegate void TestHandler(float v);
    public event TestHandler eventOnComplete;

    float time = 0;

    // Update is called once per frame
    void Update()
    {
        if (isStart)
        {
            time += Time.deltaTime;
            Debug.Log(time);
            if(time > 2)
            {
                Debug.Log("END");

                eventOnComplete?.Invoke(20);
                isStart = false;
            }
        }
    }

    [SerializeField] bool isStart = false;

    public async Task<float> AsyncEventAct(CancellationToken cancellationToken = default)
    {
        Debug.Log("AsyncEventAct");
        isStart = true;
        time = 0;

        // -----
        var tcs = new TaskCompletionSource<float>();

        // https://gist.github.com/inoook/0c99004800273ef5e857b7ecf7117ae7
        TestHandler handler = null;
        handler = (float v) =>
        {
            // イベントのクリア　初期状態へ
            eventOnComplete -= handler;
            handler = null;

            // 返り値のセット
            tcs.TrySetResult(v);
        };
        eventOnComplete += handler;

        using (cancellationToken.Register(() => {
            // イベントのクリア　初期状態へ
            eventOnComplete -= handler;
            handler = null;
            
            //
            isStart = false;

            //tcs.TrySetResult(-1);// キャンセルされても戻り値を返す場合
            tcs.TrySetCanceled();// キャンセル OperationCanceledException を発生させる場合
        }))
        {
            return await tcs.Task;
        }
    }
}