Moving Camera in SpriteKit Swift

Question

I am creating a game in sprite kit using swift, and I am trying to be able to move the SKScene around with a finger because not all of the nodes fit within the scene. I have already created world, overlay, and camera nodes with this code.

        override func didMoveToView(view: SKView) {
    world = self.childNodeWithName("world")!

    if !isCreated {
        isCreated = true

        // Camera setup
        self.anchorPoint = CGPoint(x: 0.5, y: 0.5)
        self.world = SKNode()
        self.world.name = "world"
        addChild(self.world)

        self.cam = SKNode()
        self.cam.name = "camera"
        self.world.addChild(self.cam)

        // UI setup
        self.overlay = SKNode()
        self.overlay.zPosition = 10
        self.overlay.name = "overlay"
        addChild(self.overlay)
    }

I would like to be able to move the camera around by using a pan gesture with a single finger. How would I do this? Any help would be appreciated.

Answer 1

If anybody needs it, here is an all-in-one solution:

class GameScene: SKScene {

  var previousCameraPoint = CGPoint.zero

  override func didMove(to view: SKView) {
    let panGesture = UIPanGestureRecognizer()
    panGesture.addTarget(self, action: #selector(panGestureAction(_:)))
    view?.addGestureRecognizer(panGesture)
  }

  @objc func panGestureAction(_ sender: UIPanGestureRecognizer) {
    // The camera has a weak reference, so test it
    guard let camera = self.camera else {
      return
    }
    // If the movement just began, save the first camera position
    if sender.state == .began {
      previousCameraPoint = camera.position
    }
    // Perform the translation
    let translation = sender.translation(in: self.view)
    let newPosition = CGPoint(
      x: previousCameraPoint.x + translation.x * -1,
      y: previousCameraPoint.y + translation.y
    )
    camera.position = newPosition
  }

}

Answer 2

As an alternative to @Kris's solution (which is based in UIKit), you can also monitor touches in Sprite Kit with your SKScene subclass. I wrote a small sample which should point you in the right direction.

class YourSceneSubclass : SKScene
{  
  override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
    guard let touch = touches.first else {
      return
    }

    let location = touch.locationInNode(self)
    let previousLocation = touch.previousLocationInNode(self)

    camera?.position.x += location.x - previousLocation.x
    camera?.position.y += location.y - previousLocation.y
  }
}

I didn't run this, just wrote it in a playground. Also note that if you want to handle other taps/gestures as well you will have to write additional code making sure the recognition works well for all your intended scenarios.