unity-unitask-design

Call .Preserve() once on the UniTask to memoize its backing source, then await the preserved value repeatedly. Awaiting a raw UniTask twice throws InvalidOperationException because UniTask is a struct whose pooled IUniTaskSource is recycled after the first await.

Use this.GetCancellationTokenOnDestroy() on a MonoBehaviour, GameObject, or Component, and pass the token into every cancellation-aware call like UniTask.Delay. Plain C# classes lack this extension and must own and dispose their own CancellationTokenSource.

No. UniTask.SwitchToThreadPool, UniTask.Run, and RunOnThreadPool throw NotSupportedException on WebGL because the platform is single-threaded. Guard such calls with #if UNITY_WEBGL && !UNITY_EDITOR and fall back to cooperative Yield-based work.

UniTask.Yield may resume on the same frame if awaited from an earlier PlayerLoop phase than the target timing, while NextFrame guarantees continuation on a subsequent frame. Use NextFrame to split work across frames and Yield(timing) to target a specific phase.

UniTask is a readonly struct wrapping an IUniTaskSource and a version token. After the first await, the source returns to the pool and the token becomes stale, so the second await throws InvalidOperationException. Use .Preserve() or invoke the async method again.

Use .ToUniTask() whenever you need progress reporting via IProgress<float>, cancellation via CancellationToken, or typed results like AssetBundle from AssetBundleCreateRequest. A bare await compiles but wires up none of these and can silently leak progress callbacks.