Synchronous Workflow

Synchronous Addressables APIs help to more closely mirror Unity asset loading workflows. AsyncOperationHandles now have a method called WaitForCompletion() that force the async operation to complete and return the Result of the operation.

API

TObject WaitForCompletion()

Result

The result of WaitForCompletion is the Result of the async operation it is called on. If the operation fails, this returns default(TObject).

It is possible to get a default(TObject) for a result when the operation doesn't fail. Async operations that auto release their AsyncOperationHandles on completion are such cases. Addressables.InitializeAsync() and any API with a autoReleaseHandle parameter set to true will return default(TObject) even though the operations themselves succeeded.

Performance

It is worth noting that calling WaitForCompletion may have performance implications on your runtime when compared to Resources.Load or Instantiate calls directly. If your AssetBundle is local or has been previously downloaded and cached, these performance hits are likely to be negligible. However, this may not be the case for your individual project setup.

All currently active Asset Load operations are completed when WaitForCompletion is called on any Asset Load operation, due to how Async operations are handled in the Engine. To avoid unexpected stalls, use WaitForCompletion when the current operation count is known, and the intention is for all active operations to complete synchronously.

When using WaitForCompletion, there are performance implications. When using 2021.2.0 or newer, these are minimal. Using an older version can result in delays that scale with the number of Engine Asset load calls that are loading when WaitForCompletion is called.

It is not recommended that you call WaitForCompletion on an operation that is going to fetch and download a remote AssetBundle. Though, it is possible if that fits your specific situation.

Code Sample

void Start()
{
    //Basic use case of forcing a synchronous load of a GameObject
    var op = Addressables.LoadAssetAsync<GameObject>("myGameObjectKey");
    GameObject go = op.WaitForCompletion();

    //Do work...

    Addressables.Release(op);
}