How to make a particle image bigger with a scale effect with SceneKit?

Question

I am looking for the same effect as we have in SpriteKit for the emitter particles, the scale effect that can make a particle image bigger or smaller depending on the time. (a simple red circle for example, getting bigger and disappearing after 1 second.) I cannot find the same scale option as we can find in SpriteKit. The image can be bigger and stay bigger, but it would not change depending on the time then.

Would someone know a good way to do this?

Thanks

EDIT:

None of these attempts worked, would you know why?

func addParticleSceneKit(){
        println("add")
        var fire = SCNParticleSystem(named: "circle1.scnp", inDirectory: "art.scnassets/Particles")
        fire.particleSize = 5
        emitter.addParticleSystem(fire) //emitter is a SCNNode

        /*
        let bigger = SCNAction.runBlock { (node) -> Void in
            dispatch_async(dispatch_get_main_queue(), { () -> Void in
                SCNTransaction.setAnimationDuration(1)
                fire.propertyControllers = [SCNParticlePropertySize : 10.0]
            })
        }
        emitter.runAction(bigger)
        */

        //SCNTransaction.begin()
        //SCNTransaction.setAnimationDuration(1)
        //fire.propertyControllers = [SCNParticlePropertySize : 10.0]
        //SCNTransaction.commit()
    }

Answer 1

Wow. Just wow. You've thrown a lot of code at the wall just to see what sticks, but have you looked in the documentation?

The method description for SCNParticlePropertyController's initializer includes a code example that does almost exactly what you're asking for — it animates particle sizes. Reproduced here:

// 1. Create and configure an animation object.
let animation = CAKeyframeAnimation()
animation.values = [ 0.1, 1.0, 3.0, 0.5 ]

// 2. Create a property controller from the animation object.
let sizeController = SCNParticlePropertyController(animation: animation)

// 3. Assign the controller to a particle system, associating it with a particle property.
particleSystem.propertyControllers = [ SCNParticlePropertySize: sizeController ]

If you only need a from size and a to size instead of keyframes, you can use a CABasicAnimation in step 1.