---
title: renderContextObserver
framework: audiotoolbox
role: symbol
role_heading: Instance Property
path: audiotoolbox/auaudiounit/rendercontextobserver
---

# renderContextObserver

The block that the system calls when the rendering context changes.

## Declaration

```occ
@property (nonatomic, readonly) AURenderContextObserver renderContextObserver;
```

## Discussion

Discussion Implement this property if your Audio Unit creates auxilliary realtime rendering threads. Return a block for the system to call when the rendering context changes. important: The block you provide is for system use only. Audio Unit hosts must not attempt to interact with the audio unit through this block.

## 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)
- [scheduleParameterBlock](audiotoolbox/auaudiounit/scheduleparameterblock.md)
- [maximumFramesToRender](audiotoolbox/auaudiounit/maximumframestorender.md)
- [token(byAddingRenderObserver:)](audiotoolbox/auaudiounit/token(byaddingrenderobserver:).md)
- [removeRenderObserver(_:)](audiotoolbox/auaudiounit/removerenderobserver(_:).md)
- [AURenderContextObserver](audiotoolbox/aurendercontextobserver.md)
- [AudioUnitRenderContext](audiotoolbox/audiounitrendercontext.md)
- [AURenderObserver](audiotoolbox/aurenderobserver.md)