Error with Dispatch Queue Swift - swift

Question

I am trying to create a genetic algorithm for running race cars around a race track. Each car gets random instructions that apply a force to the car and rotate the car by a certain number of degrees. In order to space out the new instructions given to each car, I used a delay time in dispatch Queue that adds 0.2 seconds to the previous instruction.
e.g.
0 seconds - first instruction
0.2 seconds - second instruction
0.4 seconds -third instruction
and so on...
The problem I have is that after several instructions have been carried out I start to notice a longer delay between instructions, to the point where a new instruction is applied after say 2 seconds.
Here is my code below.
func carAction(newCar: [[CGFloat]], racecar: SKSpriteNode) {
var caralive = true
let max = 1000
var count = 0
let delayTime = 200000000
var deadlineTime = DispatchTime.now()
while count < max {
let angleChange = newCar[count][1]
let speedChange = newCar[count][0]
count += 1
deadlineTime = deadlineTime + .nanoseconds(delayTime)
DispatchQueue.main.asyncAfter(deadline: deadlineTime) {
if caralive == true {
print(DispatchQueue.main)
racecar.physicsBody?.angularVelocity = 0
let rotate = SKAction.rotate(byAngle: (angleChange * .pi / 180), duration: 0.2)
racecar.run(rotate)
let racecarRotation : CGFloat = racecar.zRotation
var calcRotation : Float = Float(racecarRotation) + Float(M_PI_2)
let Vx = speedChange * CGFloat(cosf(calcRotation))
let Vy = speedChange * CGFloat(sinf(calcRotation))
let force = SKAction.applyForce(CGVector(dx: Vx, dy: Vy), duration: 0.2)
racecar.run(force)
let total = self.outerTrack.count
var initial = 0
while initial < total {
if racecar.intersects(self.outerTrack[initial]) {
racecar.removeFromParent()
self.numberOfCars -= 1
initial += 1
caralive = false
break
} else {
initial += 1
}
}
} else {
// print(self.numberOfCars)
}
}
}
The 2D array newCar is a list of all the instructions.
Any help would be massively appreciated as I have been trying to figure this out for ages now!!
Many thanks in advance, any questions just feel free to ask!

Answer 1

You should do something like this instead:
func scheduledTimerWithTimeInterval(){
// Scheduling timer to Call the function "updateCounting" with the interval of 1 seconds
timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("moveCarsFunction"), userInfo: nil, repeats: true)
}
And call scheduledTimerWithInterval once
originally answered here