UniTask详解_unitask库

UniTask

安装

git: https://github.com/Cysharp/UniTask
https://gitee.com/cloudlin/UniTask.git

可以直接下载包进行导入: https://github.com/Cysharp/UniTask/releases
也可以通过PackageManager添加第3方git插件

常见用法

	// extension awaiter/methods can be used by this namespace
	using Cysharp.Threading.Tasks;

	// You can return type as struct UniTask<T>(or UniTask), it is unity specialized lightweight alternative of Task<T>
	// zero allocation and fast excution for zero overhead async/await integrate with Unity
	
	//	所有任务都要能接受1个 CancellationToken 参数用来取消
	async UniTask<string> Test1(CancellationToken cancellationToken)
	{
   
		// 可以等待所有 AsyncOperation Request IEnumerator  Task 
		// 等待异步操作系列，底层分2种实现，不能取消的直接通过 asyncOperation.completed += 注册事件
		// 能取消的会转成每帧检测，所以能更新进度，检测到 asyncOperation.isDone 时就完成
		// 参考 UnityAsyncExtensions.cs AsyncOperationConfiguredSource.MoveNext
		var asset = await Resources.LoadAsync<TextAsset>("foo");
		var txt = (await UnityWebRequest.Get("https://...").SendWebRequest()).downloadHandler.text;
		
		//	await LoadSceneAsync().ToUniTask() 会导致场景中脚本的  Start 函数和 await 后代码的顺序问题
		//	因为 ToUniTask 和 WithCancellation 使用不同于 await AsyncOperation 的定时方式，
		//	因此加载场景后面不要加 .ToUniTask 和 .WithCancellation
		await SceneManager.LoadSceneAsync("scene2");
		//	如果你想处理取消请求，可以 LoadSceneAsync 在之后调用 ThrowIfCancellationRequested
		//		等价于 if (IsCancellationRequested)ThrowOperationCanceledException();
		cancellationToken.ThrowIfCancellationRequested();
		
		//	在 async 函数中你可以主动抛出 CanceledException 异常来取消函数执行
		throw new OperationCanceledException();
		
		// .WithCancellation enables Cancel, GetCancellationTokenOnDestroy synchornizes with lifetime of GameObject
		var asset2 = await Resources.LoadAsync<TextAsset>("bar").WithCancellation(this.GetCancellationTokenOnDestroy());

		// .ToUniTask accepts progress callback(and all options), Progress.Create is a lightweight alternative of IProgress<T>
		var asset3 = await Resources.LoadAsync<TextAsset>("baz").ToUniTask(Progress.Create<float>(x => Debug.Log(x)));

		// get async webrequest
		async UniTask<string> GetTextAsync(UnityWebRequest req)
		{
   
			var op = await req.SendWebRequest();
			return op.downloadHandler.text;
		}



		var task1 = GetTextAsync(UnityWebRequest.Get("http://google.com"));
		var task2 = GetTextAsync(UnityWebRequest.Get("http://bing.com"));
		var task3 = GetTextAsync(UnityWebRequest.Get("http://yahoo.com"));
		
		//	等待所有，注意这个没有取消操作??
		//	参考 UniTask.WhenAll.cs
		// concurrent async-wait and get results easily by tuple syntax
		var (google, bing, yahoo) = await UniTask.WhenAll(task1, task2, task3);
		// shorthand of WhenAll, tuple can await directly
		var (google2, bing2, yahoo2) = await (task1, task2, task3);
		
		//	等待任意，注意这个没有取消操作??，而且当1个完成时其它的不会取消等待，只是其它的完成后不会再调用回调而已 
		//var ret = await UniTask.WhenAny(task1, task2, task3);



		//	等待时间系列，底层全部是每帧进行判断，到时间就执行
		//	默认不会自动取消，当你传入 cancellationToken 并触发取消时并不会马上取消监听
		//	而是在下一帧(不管等待多少帧或多少秒)更新时，检测到 cancellationToken.IsCancellationRequested 返回false才会移除监听器
		//	参考 UniTask.Delays.cs DelayPromise.MoveNext
		
		// await frame-based operation like a coroutine
		await UniTask.DelayFrame
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