Class

CAReplicatorLayer

A layer that creates a specified number of copies of its sublayers (the source layer), each copy potentially having geometric, temporal, and color transformations applied to it.

Overview

You can use a CAReplicatorLayer object to build complex layouts based on a single source layer that is replicated with transformation rules that can affect the position, rotation color, and time.

The code in Listing 1 shows a simple example: a red square is added to a replicator layer with an instance count of 5. The position of each replicated instance is offset along the x axis so that it appears to the right of the previous instance. The blue and green color channels are offset so that their values reach 0 at the final instance.

Listing 1

Using a replicator layer

let replicatorLayer = CAReplicatorLayer()
     
let redSquare = CALayer()
redSquare.backgroundColor = NSColor.white.cgColor
redSquare.frame = CGRect(x: 0, y: 0, width: 100, height: 100)
     
let instanceCount = 5
     
replicatorLayer.instanceCount = instanceCount
replicatorLayer.instanceTransform = CATransform3DMakeTranslation(110, 0, 0)
     
let offsetStep = -1 / Float(instanceCount)
replicatorLayer.instanceBlueOffset = offsetStep
replicatorLayer.instanceGreenOffset = offsetStep
    
replicatorLayer.addSublayer(redSquare)

The result of the code above is a row of five squares, with colors graduating from white to red, as shown in Figure 1.

Figure 1

Replicator layer example

Replicator layer example

Replicator layers can be nested. The code in Listing 2 adds replicatorLayer to a second replicator layer that offsets the position of each instance vertically and subtracts from the red channel.

Listing 2

Nesting replicator layers

let outerReplicatorLayer = CAReplicatorLayer()

outerReplicatorLayer.addSublayer(replicatorLayer)

outerReplicatorLayer.instanceCount = instanceCount
outerReplicatorLayer.instanceTransform = CATransform3DMakeTranslation(0, 110, 0)
outerReplicatorLayer.instanceRedOffset = offsetStep

The result of adding the code in Listing 2 is to create a grid with the value of the red channel being reduced in the vertical direction, as shown in Figure 2.

Figure 2

Nested replicator layer example

Nested replicator layer example

Symbols

Setting Instance Display Properties

var instanceCount: Int

The number of copies to create, including the source layers.

var instanceDelay: CFTimeInterval

Specifies the delay, in seconds, between replicated copies. Animatable.

var instanceTransform: CATransform3D

The transform matrix applied to the previous instance to produce the current instance. Animatable.

Modifying Instance Layer Geometry

var preservesDepth: Bool

Defines whether this layer flattens its sublayers into its plane.

Accessing Instance Color Values

var instanceColor: CGColor?

Defines the color used to multiply the source object. Animatable.

var instanceRedOffset: Float

Defines the offset added to the red component of the color for each replicated instance. Animatable.

var instanceGreenOffset: Float

Defines the offset added to the green component of the color for each replicated instance. Animatable.

var instanceBlueOffset: Float

Defines the offset added to the blue component of the color for each replicated instance. Animatable.

var instanceAlphaOffset: Float

Defines the offset added to the alpha component of the color for each replicated instance. Animatable.

Relationships

Inherits From

Conforms To