---
title: "init(animation:)"
framework: scenekit
role: symbol
role_heading: Initializer
path: "scenekit/scnparticlepropertycontroller/init(animation:)"
---

# init(animation:)

Creates a particle property controller with the specified Core Animation animation.

## Declaration

```swift
convenience init(animation: CAAnimation)
```

## Parameters

- `animation`: A Core Animation object specifying the behavior of the property animation. Must not be nil. You can use different doc://com.apple.documentation/documentation/QuartzCore/CAAnimation subclasses to animate effects in different ways. For example, a doc://com.apple.documentation/documentation/QuartzCore/CABasicAnimation instance transitions a property from one value to another, and a doc://com.apple.documentation/documentation/QuartzCore/CAKeyframeAnimation instance transitions a property through a series of values. You use properties of the animation object to define its timing curve, repeat mode, and other options. SceneKit ignores the doc://com.apple.documentation/documentation/QuartzCore/CAPropertyAnimation/keyPath, doc://com.apple.documentation/documentation/QuartzCore/CAMediaTiming/duration, and doc://com.apple.documentation/documentation/QuartzCore/CAMediaTiming/repeatCount properties of this animation object.

## Return Value

Return Value A new particle property controller.

## Discussion

Discussion To set up a particle property animation: Create a CAAnimation object defining how a property of each particle in the system changes over time. Create a particle property controller using the init(animation:) method. Attach the property controller to a particle system using the propertyControllers dictionary, choosing a key listed in Particle Property Keys to identify the particle property it animates. For example, the following code sets up a controller to animate particle sizes: // 1. Create and configure an animation object. CAKeyframeAnimation *animation = [CAKeyframeAnimation animation]; animation.values = @[ @0.1, @1.0, @3.0, @0.5 ];   // 2. Create a property controller from the animation object. SCNParticlePropertyController *controller =     [SCNParticlePropertyController controllerWithAnimation:animation];   // 3. Assign the controller to a particle system, associating it with a particle property. particleSystem.propertyControllers = @{ SCNParticlePropertySize: controller };