Simultaneous gestures and scaling of pinch Gesture in swift - swift

Question

Hopeing for a bit of enlightenment. I have a piece of code. Which is working fairly OK.
I have 2 gestures implemented - pinch and rotate.
let pinchGesture = UIPinchGestureRecognizer(target: self, action: #selector(pinchAction(sender:)))
view.addGestureRecognizer(pinchGesture)
pinchGesture.delegate = self
let rotateGesture = UIRotationGestureRecognizer(target: self, action: #selector(rotateAction(sender:)))
view.addGestureRecognizer(rotateGesture)
rotateGesture.delegate = self
and then this function which I found here on another thread.
func gestureRecognizer(_ gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWith otherGestureRecognizer: UIGestureRecognizer) -> Bool {
if (gestureRecognizer is UIPanGestureRecognizer || gestureRecognizer is UIRotationGestureRecognizer) {
return true
} else {
return false
}
}
my class is set to
class GameScene: SKScene, UIGestureRecognizerDelegate {
so my first question is. How the heck is this function actually being called? Is it automatically called because it's called gestureRecognizer? I don't call it elsewhere as a function in my code. Sorry just find it confusing.
the other interesting issue is that as I rescale my SKSprite node with the pinch function I want it to not jump back to the scale of the initial pinch. I have set a variable for the scale of the node being adjusted and take that in the pinch began and also adjust the variable when pinch ends as so:
#objc func pinchAction(sender:UIPinchGestureRecognizer){
if sender.state == .began{
//print("Pinch Began")
pointer.setScale(CGFloat(protractorScale * 0.5))
protractor.setScale(CGFloat(protractorScale * 0.45))
}
if sender.state == .changed{
// print("Pinch Change")
let newScale = sender.scale
protractorScale = Double(newScale)
print(newScale)
pointer.setScale(CGFloat(protractorScale * 0.5))
protractor.setScale(CGFloat(protractorScale * 0.45))
ballSpeed = Float(newScale * 500)
}
if sender.state == .ended{
// print("Pinch Ended")
let newScale = sender.scale
protractorScale = Double(newScale)
}
}
but it still jumps to whatever pinch position I start with while it ought to stay stable between individual pinches rather than reseting.
I appreciate my code is simplistic so am also open to suggestions for a tighter code. This is my first attempt at using simultaneous gestures.Thanks

Answer 1

I finally understood that obviously the pinch gesture always initially returns a pinch scale factor of 1. Obviously! Once I realised that and after KnightOfDragon's advice it was straightforward.
#objc func pinchAction(sender:UIPinchGestureRecognizer){
if sender.state == .began{
let startScale = sender.scale
print("initial pinch scale \(startScale)")
pointer.setScale(CGFloat(protractorScale))
protractor.setScale(CGFloat(protractorScale))
}
if sender.state == .changed{
let getScale = sender.scale
print(getScale)
let newScale = (CGFloat(protractorScale) * getScale)
pointer.setScale(newScale)
protractor.setScale(newScale)
ballSpeed = Float(newScale * 100)
ballSpeedIndicator.text = "\(Int(ballSpeed))"
}
if sender.state == .ended{
// print("Pinch Ended")
let newScale = sender.scale
protractorScale = protractorScale * Double(newScale)
}
}
I set my initial node scale also to 1 as a global variable. So now in the state ended I return that * the pinch scale and the scaling now remains perfectly stable.