How to reference the node from within a custom SKAction Swift - swift

Question

I can create a custom SKAction as follows:
extension SKAction {
class func move(from: CGPoint, halfWayTo: CGPoint, duration: TimeInterval) -> SKAction {
let midPoint = CGPoint(x: (from.x + halfWayTo.x)/2, y: (from.y + halfWayTo.y)/2 )
return SKAction.move(to: midPoint, duration: duration)
}
}
which I then use like this:
//Setup
let node = SKNode()
node.position = CGPoint(x: 50, y: 50)
let destination = CGPoint(x: 100, y: 100)
//Move from node's current position half way towards the destination
let action = SKAction.move(from: node.position, halfWayTo: destination, duration: 1)
node.run(action)
but in keeping with the standard:
SKAction.move(to: destination, duration: 1)
I would rather be able to say:
let action = SKAction.move(halfWayTo: destination, duration: 1)
node.run(action)
but I don't know how to refer to 'node' from inside the custom SKAction so that I can get it's position and calculate the halfway point?

Answer 1

You use self.
extension SKAction {
class func move(halfWayTo: CGPoint, duration: TimeInterval) -> SKAction {
let from = self.position
let midPoint = CGPoint(x: (from.x + halfWayTo.x)/2, y: (from.y + halfWayTo.y)/2 )
return SKAction.move(to: midPoint, duration: duration)
}
}
Then call with (as you said)
node.move(halfWayTo: B, duration: 1)

Answer 2

I'm still not sure whether the SKAction has a reference to the node it is applied to - even when it's running - or even if it does I'm not sure whether there's a way to access it. If anyone knows that it does please let me know.
I've thought of one approach as follows:
Instead of extending SKAction, extend SKNode as follows:
extension SKNode {
func move(halfWayTo: CGPoint, duration: TimeInterval) -> SKAction {
let from = self.position
let midPoint = CGPoint(x: (from.x + halfWayTo.x)/2, y: (from.y + halfWayTo.y)/2 )
return SKAction.move(to: midPoint, duration: duration)
}
}
and then use as follows:
//Setup
let node = SKNode()
node.position = CGPoint(x: 50, y: 50)
let destination = CGPoint(x: 100, y: 100)
//Move from node's current position half way towards the destination
let action2 = node.move(halfWayTo: destination, duration: 1)
node.run(action2)