# compositingFilter A CoreImage filter used to composite the layer and the content behind it. Animatable. ``` var compositingFilter: Any? { get set } ``` ## Discussion The default value of this property is `nil`, which causes the layer to use source-over compositing. Although you can use any Core Image filter as a layer’s compositing filter, for best results, use those in the [CICategoryCompositeOperation](https://developer.apple.com/library/archive/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html#//apple_ref/doc/uid/TP30000136-SW71) category. In macOS, it is possible to modify the filter’s parameters after attaching it to the layer but you must use the layer’s method to do so. For example, to change the `inputRadius` parameter of the filter, you could use code similar to the following: ```objc CIFilter *filter = ...; CALayer *layer = ...; layer.compositingFilter = filter; [layer setValue:[NSNumber numberWithInt:1] forKeyPath:@"compositingFilter.inputRadius"]; ``` Changing the inputs of the object directly after it is attached to the layer causes undefined behavior. The following code shows how to create two overlapping text layers, background and foreground. Addition compositing is used to composite the foreground over the background. ```swift view.layer = CALayer() view.layerUsesCoreImageFilters = true let background = CATextLayer() background.string = "background" background.foregroundColor = NSColor.gray.cgColor background.backgroundColor = NSColor.darkGray.cgColor background.alignmentMode = kCAAlignmentCenter background.fontSize = 96 background.frame = CGRect(x: 10, y: 10, width: 640, height: 160) let foreground = CATextLayer() foreground.string = "foreground" foreground.foregroundColor = NSColor.lightGray.cgColor foreground.backgroundColor = NSColor.darkGray.cgColor foreground.alignmentMode = kCAAlignmentCenter foreground.fontSize = 48 foreground.opacity = 0.5 foreground.frame = CGRect(x: 20, y: 20, width: 600, height: 60) foreground.masksToBounds = false if let compositingFilter = CIFilter(name: "CIAdditionCompositing") { foreground.compositingFilter = compositingFilter } view.layer?.addSublayer(background) background.addSublayer(foreground) ``` The following figure shows the result: the identical background colors of the two layers are added together so that a brighter gray is produced where the layers overlap.  The following figure shows the default result when the foreground layer’s compositing filter is `nil` or [CISourceOverCompositing](https://developer.apple.com/library/archive/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html#//apple_ref/doc/filter/ci/CISourceOverCompositing).  ### Special Considerations This property is not supported on layers in iOS. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)