---
title: isAsynchronous
framework: quartzcore
role: symbol
role_heading: Instance Property
path: quartzcore/caopengllayer/isasynchronous
---

# isAsynchronous

Determines when the contents of the layer are updated.

## Declaration

```swift
var isAsynchronous: Bool { get set }
```

## Discussion

Discussion If false, the contents of the layer are updated only in response to receiving a setNeedsDisplay() message. When true, the receiver’s canDraw(inCGLContext:pixelFormat:forLayerTime:displayTime:) is called periodically to determine if the OpenGL content should be updated.

## See Also

### Related Documentation

- [Core Animation Programming Guide](apple-archive/documentation/Cocoa/Conceptual/CoreAnimation_guide/Introduction.md)

### Drawing Layer Content

- [canDraw(inCGLContext:pixelFormat:forLayerTime:displayTime:)](quartzcore/caopengllayer/candraw(incglcontext:pixelformat:forlayertime:displaytime:).md)
- [draw(inCGLContext:pixelFormat:forLayerTime:displayTime:)](quartzcore/caopengllayer/draw(incglcontext:pixelformat:forlayertime:displaytime:).md)