Guide for UniTask and Awaitable in Unity 6

[neuecc]

Unity 6 introduces the awaitable type, Awaitable. To put it simply, Awaitable can be considered a subset of UniTask, and in fact, Awaitable's design was influenced by UniTask. It should be able to handle PlayerLoop-based awaits, pooled Tasks, and support for cancellation with CancellationToken in a similar way. With its inclusion in the standard library, you may wonder whether to continue using UniTask or migrate to Awaitable. Here's a brief guide.

First, the functionality provided by Awaitable is equivalent to what coroutines offer. Instead of yield return, you use await; await NextFrameAsync() replaces yield return null; and there are equivalents for WaitForSeconds and EndOfFrame. However, that's the extent of it. Being coroutine-based in terms of functionality, it lacks Task-based features. In practical application development using async/await, operations like WhenAll are essential. Additionally, UniTask enables many frame-based operations (such as DelayFrame) and more flexible PlayerLoopTiming control, which are not available in Awaitable. Of course, there's no Tracker Window either.

Therefore, I recommend using UniTask for application development. UniTask is a superset of Awaitable and includes many essential features. For library development, where you want to avoid external dependencies, using Awaitable as a return type for methods would be appropriate. Awaitable can be converted to UniTask using AsUniTask, so there's no issue in handling Awaitable-based functionality within the UniTask library. Of course, if you don't need to worry about dependencies, using UniTask would be the best choice even for library development.