Understanding Spritekit run block, variable not as expected - swift

Question

I'm looking for some help understanding why my speedToPoint variable is always 1 when it gets to the wait action.
This is part of an SKSpriteNode extension i wrote for making a bird fly to a random point in a predefined rectangle. The speedToPoint is also randomized between 1 and 4 and used as the duration for the moveTo action. However, i also need to use that TimeInterval for my wait block in the action sequence.
speedToPoint is indeed being randomized in the run block (i've confirmed). How can i use that same randomized number in the wait block in the next part of the sequence?
var speedToPoint:TimeInterval = 1
self.run(SKAction.repeatForever(
SKAction.sequence([
SKAction.run{
speedToPoint = TimeInterval(Globals.sharedInstance.randomF(min: 1, max: 4))
var pointX = Globals.sharedInstance.randomF(min: left,max: right)
let pointY = Globals.sharedInstance.randomF(min: top,max:bottom)
while abs(self.position.x.distance(to: pointX)) < 200 {
pointX = Globals.sharedInstance.randomF(min: left,max: right)
}
self.xScale = pointX < self.position.x ? -1 : 1
self.run(SKAction.move(to: CGPoint(x:pointX,y:pointY),duration: speedToPoint))
},
SKAction.wait(forDuration: speedToPoint)])
),withKey: "inFrame")
To clarify, what i'm really tring to do is have the bird fly to a point, once it's arrived at that point, fly to another point. I'm still wrapping my heard around action sequences and whether or not they actually wait for completion to move on. Which from what i've read, they do, but not for any move actions. That's why the wait is in there. Perhaps there is another way?

Answer 1

An SKAction, once created, can't be modified, and it is meant to be reused eg. you can't modify the duration parameter, or change other passed parameters. This means that you have to re-create it if you need it changed. Of course you can change the speed property of an existing action, or you can pause the action but that's pretty much it when it comes to modifying the existing action.
To solve your issue, you could do next:
1) Create an action which moves a sprite to a specific location
2) Once the action is completed, you create a new one which does the same
you can do this using recursion, like this (just copy & paste the code to see how it works):
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
private var bird = SKSpriteNode(color: .purple, size: CGSize(width: 100, height: 100))
override func didMove(to view: SKView) {
addChild(bird)
recursive()
}
func recursive(){
let sequence = SKAction.sequence([
SKAction.move(to: self.randomPoint(inRect: self.frame), duration: TimeInterval(self.random(between: 1, and: 3))),
SKAction.run({[unowned self] in NSLog("Block executed"); self.recursive()})
])
self.bird.run(sequence, withKey: "aKey")
}
func random(between minimum: CGFloat, and maximum: CGFloat) -> CGFloat{
return CGFloat(arc4random()) / CGFloat(UINT32_MAX) * abs(minimum - maximum) + min(minimum, maximum)
}
func randomPoint(inRect rect:CGRect)->CGPoint{
let x = random( between: -rect.size.width / 2.0 , and: rect.origin.x + rect.size.width/2.0)
let y = random(between: -rect.size.height / 2.0 , and: rect.origin.y + rect.size.height/2.0)
return CGPoint(x: x, y: y)
}
}
To stop this action, remove the key associated with it.