How to use pinch gesture in game scene - swift

Question

I need your help guys. I have game scene and func which allow to move camera using panGesture. Also i need pinchGesture to zoom in and out my SKScene. I found some code here, but it lags. Can plz someone help me to improve this code?
`
#objc private func didPinch(_ sender: UIPinchGestureRecognizer) {
guard let camera = self.camera else {return}
if sender.state == .changed {
previousCameraScale = camera.xScale
}
camera.setScale(previousCameraScale * 1 / sender.scale)
sender.scale = 1.0
}
`

Answer 1

try this pinch code.
//pinch -- simple version
#objc func pinch(_ recognizer:UIPinchGestureRecognizer) {
guard let camera = self.camera else { return } // The camera has a weak reference, so test it
if recognizer.state == .changed {
let deltaScale = (recognizer.scale - 1.0)*2
let convertedScale = recognizer.scale - deltaScale
let newScale = camera.xScale*convertedScale
camera.setScale(newScale)
//reset value for next time
recognizer.scale = 1.0
}
}
although i would recommend this slightly more complicated version which centers the pinch around the touch point. makes for a much nicer pinch in my experience.
//pinch around touch point
#objc func pinch(_ recognizer:UIPinchGestureRecognizer) {
guard let camera = self.camera else { return } // The camera has a weak reference, so test it
//cache location prior to scaling
let locationInView = recognizer.location(in: self.view)
let location = self.convertPoint(fromView: locationInView)
if recognizer.state == .changed {
let deltaScale = (recognizer.scale - 1.0)*2
let convertedScale = recognizer.scale - deltaScale
let newScale = camera.xScale*convertedScale
camera.setScale(newScale)
//zoom around touch point rather than center screen
let locationAfterScale = self.convertPoint(fromView: locationInView)
let locationDelta = location - locationAfterScale
let newPoint = camera.position + locationDelta
camera.position = newPoint
//reset value for next time
recognizer.scale = 1.0
}
}
//also need these extensions to add and subtract CGPoints
extension CGPoint {
static func + (a:CGPoint, b:CGPoint) -> CGPoint {
return CGPoint(x: a.x + b.x, y: a.y + b.y)
}
static func - (a:CGPoint, b:CGPoint) -> CGPoint {
return CGPoint(x: a.x - b.x, y: a.y - b.y)
}
}