How to pulse a sprite using SpriteKit in SWIFT

Question

I am attempting to "pulse" a sprite in SK/SWIFT. My attempts were crude using For-loops and .setScale , but they were not working (no errors - just no animation). I feel that using SKActions would perhaps be more elegant.

After using some help from below here is my current implementation. However, it is coming up with compile errors;

Expected member name or constructor call after type name & Consecutive statement on a line must be separated by a ;

Here is the code I am using:

SKAction *pulseUp = [SKAction.scaleTo(3.0, duration: 3.0)]
SKAction *pulseDown = [SKAction.scaleTo(1.0, duration: 3.0)]
SKAction *pulse = [SKAction.sequence(pulseUp, pulseDown)]
SKAction *repeat = [SKAction repeatActionForever:pulse]]
[self.playButton runAction: repeat]

Any help would be greatly appreciated.

Answer 1

In xCode Version 8.3.3 with Swift,

    let pulseUp = SKAction.scale(to: 3.0, duration: 1.0)
    let pulseDown = SKAction.scale(to: 0.5, duration: 1.0)
    let pulse = SKAction.sequence([pulseUp, pulseDown])
    let repeatPulse = SKAction.repeatForever(pulse)
    self.playButton.run(repeatPulse)

Answer 2

It will be similar to something like this:

 SKAction *scaleUpAction = [SKAction ...]; // you need to find the CCScaleTo counterpart
 SKAction *scaleDownAction = [SKAction ...];
 SKAction *pulse = [SKAction sequence:@[scaleUpAction, scaleDownAction]];

 [sprite runAction:[SKAction repeatActionForever:pulse]];

Answer 3

As extension :

    import SpriteKit


    extension SKSpriteNode {

    

    private static let fillColor = UIColor(red: 0, green: 0.455, blue: 0.756, alpha: 0.45)

    

    func addPulseEffect(circleOfRadius: CGFloat, backgroundColor: UIColor = fillColor) {

        

        let circle = SKShapeNode(circleOfRadius: circleOfRadius)

        circle.fillColor = backgroundColor

        circle.lineWidth = 0.0

        circle.position = CGPoint(x: 0, y: 0)

        self.addChild(circle)

        let scale = SKAction.scale(to: 3.0, duration: 1.0)

        let fadeOut = SKAction.fadeOut(withDuration: 1.0)

        let pulseGroup = SKAction.sequence([scale, fadeOut])

        let repeatSequence = SKAction.repeatForever(pulseGroup)

        circle.run(repeatSequence)

        

    }

    

    func repeatPulseEffectForEver(circleOfRadius: CGFloat) {

        let _ = Timer.scheduledTimer(withTimeInterval: 0.8, repeats: true) { (timer) in

            self.addPulseEffect(circleOfRadius: circleOfRadius)

        }

    }

}

Answer 4

If you want a real pulse effect (ie. once scaled up, instantly get to original scale and repeat for ever, do as follows:

func addPulseAction(scale: CGFloat = 50, duration: TimeInterval = 0.5) {

    let pulse = = SKAction.sequence([
        SKAction.group([
            SKAction.scale(to: scale, duration: duration),
            SKAction.fadeOut(withDuration: duration)
        ]),
        SKAction.group([
            SKAction.scale(to: 1, duration: 0),
            SKAction.fadeIn(withDuration: 0)
        ])
    ])
    let shockwave = SKShapeNode(circleOfRadius: 1)
    node.addChild(shockwave)

    shockwave.run(SKAction.repeatForever(pulse))
}