Changing the time interval of a Timer in swift spritekit

Question

So, I have this timer that is setup to run a specific function (which are both shown below) on a time interval variable called 'frequency' when I try and change the timeinterval variable frequency to a lower number based on the score number it doesn't seem to change the rate at which it fires it just seems to fire at the same time even if the frequency is changed to a lower number

override func didMove(to view: SKView) {

   Timer.scheduledTimer(timeInterval: frequency, target: self, selector: #selector(GameScene.spawnFallingOjects), userInfo: nil, repeats: true)

}


func spawnFallingOjects() {

    if (GameState.current == .playing || GameState.current == .blackstone) {

        guard usingThirdEye == false else { return }

        let scoreLabel = childNode(withName: "scoreLabel") as! Score
        let lane = [-100, -50 , 0, 50, 100]
        let duration = 3.0

        switch scoreLabel.number {

                case 0...50:
                    frequency = 6.0
                    print("frequency has changed: \(frequency)")
                case 51...100:
                    frequency = 4.5
                    print("frequency has changed: \(frequency)")
                case 101...200000:
                    frequency = 1.1
                    print("frequency has changed: \(frequency)")

                default:
                    return
        }

        let randomX = lane[Int(arc4random_uniform(UInt32(lane.count)))]

        let object:Object = Object()
        object.createFallingObject()
        object.position = CGPoint(x: CGFloat(randomX), y: self.size.height)
        object.zPosition = 20000
        addChild(object)


        let action = SKAction.moveTo(y: -450, duration: duration)
        object.run(SKAction.repeatForever(action))

     }

  }

How do I make the timer fire faster when the frequency number changes to a lower number? should I recreate the timer at the end of the function?

Read this http://stackoverflow.com/questions/23978209/spritekit-creating-a-timer — Epsilon, Dec 20 '16 at 08:11
Astrum, this is not the way to go in SpriteKit. Mainly because there is no a convenient way of pausing feature. Timers like from your example are not paired with a game loop. Use SKActions or update: method...Like described in Steffen's answer from the link above. — Whirlwind, Dec 20 '16 at 09:26

score 2 · Accepted Answer · answered Dec 20 '16 at 13:17

2

You should actually avoid using Timer, Sprite kit has its own time functionality, and Timer does not work well with it and is a real pain to manage.

Instead, use SKAction's to wait and fire:

let spawnNode = SKNode()
override func didMove(to view: SKView) {
   let wait = SKAction.wait(forDuration:frequency)
   let spawn = SKAction.run(spawnFallingObjects)
   spawnNode.run(SKAction.repeatForever(SKAction.sequence([wait,spawn])))
   addChild(spawnNode)
}

Then to make it faster, just do:

switch scoreLabel.number {

            case 0...50:
                spawnNode.speed = 1
                print("speed has changed: \(spawnNode.speed)")

            case 51...100:
                spawnNode.speed = 1.5
                print("speed has changed: \(spawnNode.speed)")

            case 101...200000:
                spawnNode.speed = 2
                print("speed has changed: \(spawnNode.speed)")

            default:
                return
    }

answered Dec 20 '16 at 13:17

Knight0fDragon

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Thanks that worked and thanks for the advice on the timers i didn't see that post while i was searching around. – Astrum Dec 20 '16 at 13:39
@KnightOfDragon Sorry, Can I ask where you are putting the Switch Statement? In a function or in update or somewhere else? – Eric.18 Feb 25 '17 at 21:36
@Eric.18 what are you trying to do, this answer is very user specific – Knight0fDragon Feb 25 '17 at 22:37
@KnightOfDragon I am trying to do a similar thing of increasing the rate of node creation based on score. I don't want to highjack this question though. This post helped me change from timer to SKAction. I just don't understand how the function is being called. – Eric.18 Feb 27 '17 at 21:14
I wouldn't even use this approach, use didSet on your score variable. Then whenever your score gets set , check to see what the new speed should be – Knight0fDragon Feb 27 '17 at 21:20
Thanks for the quick replies. I just do not get it. My game is probably set up wrong. – Eric.18 Feb 27 '17 at 22:40
create a new question or open a chat room, post some code, and I will help you out – Knight0fDragon Feb 28 '17 at 14:00

score 0 · Answer 2 · answered Dec 20 '16 at 06:25

The timeInterval property of Timer is a readonly property. (And your code is not trying to write a new frequency into the property...)

should I recreate the timer at the end of the function?

Nearly yes. Just you have no need to do it at the end.

With changing your method header like this:

func spawnFallingOjects(_ timer: Timer) {

You can access the fired Timer through the parameter timer, so you may need to write something like this just after switch scoreLabel.number {...}:

        if frequency != timer.timeInterval {
            //Invalidate old Timer...
            timer.invalidate()
            //And then allocate new one
            Timer.scheduledTimer(timeInterval: frequency, target: self, selector: #selector(GameScene.spawnFallingOjects), userInfo: nil, repeats: true)
        }

You can modify the fireDate property of an existing Timer (in case which still isValid), but recreating a Timer instance is not a heavy operation (comparing to creating an SKSpriteNode instance), so recreating a new Timer seems to be a little bit easier.

Changing the time interval of a Timer in swift spritekit

2 Answers2