---
title: scheduleParameterBlock
framework: audiotoolbox
role: symbol
role_heading: Instance Property
path: audiotoolbox/auaudiounit/scheduleparameterblock
---

# scheduleParameterBlock

The block that hosts use to schedule parameters.

## Declaration

```swift
var scheduleParameterBlock: AUScheduleParameterBlock { get }
```

## Mentioned in

Migrating Your Audio Unit Host to the AUv3 API

## Discussion

Discussion As with the render block, a host should fetch this block before beginning to render, if it intends to schedule parameters. The block is safe to call from any thread context, including realtime audio render threads. Subclasses should not override this; it is implemented in the base class and will schedule the events to be provided to the internalRenderBlock implementation This version 3 property is bridged to the version 2 AudioUnitScheduleParameters(_:_:_:) API.

## See Also

### Managing the Render Cycle

- [allocateRenderResources()](audiotoolbox/auaudiounit/allocaterenderresources().md)
- [deallocateRenderResources()](audiotoolbox/auaudiounit/deallocaterenderresources().md)
- [reset()](audiotoolbox/auaudiounit/reset().md)
- [renderResourcesAllocated](audiotoolbox/auaudiounit/renderresourcesallocated.md)
- [renderBlock](audiotoolbox/auaudiounit/renderblock.md)
- [maximumFramesToRender](audiotoolbox/auaudiounit/maximumframestorender.md)
- [token(byAddingRenderObserver:)](audiotoolbox/auaudiounit/token(byaddingrenderobserver:).md)
- [removeRenderObserver(_:)](audiotoolbox/auaudiounit/removerenderobserver(_:).md)
- [AURenderObserver](audiotoolbox/aurenderobserver.md)