如何在 SpriteKit 中创建有限的、可滚动的背景？

Question

I'm looking to have a scrollable background in Sprite Kit. I've had a go with some of the other solutions available online, but they were implementing infinite scrolling backgrounds, and I haven't been able to adapt the code to my needs.

Here is some sample code which I've got to try and get the background moving (without the detection of reaching the end of the background) - but it's very choppy and not smooth at all.

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touchLocation = touches.first?.location(in: self), let node = nodes(at: touchLocation).first {
        if node.name != nil {
            if node.name == "background" {
                background.position = touchLocation
            }
        }
    }
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touchLocation = touches.first?.location(in: self), let node = nodes(at: touchLocation).first {
        if node.name != nil {
            if node.name == "background" {
                background.position = touchLocation
            }
        }
    }
}

The image below demonstrates what I'm trying to achieve - I want the code to detect when you've reached the end of the background, and to prevent you from moving it any further.

Answer 1

So, taking @KnightOfDragon's comment into account about needing to set maximum and minimum X coordinate values for the background, I was able to solve my own question. I already had swipe left/right recognisers in my code (for another purpose in my game), and I was able to reuse these to fulfil my needs. Code is as follows:

In didMove() :

swipeRightRec.addTarget(self, action: #selector(self.swipedRight) )
swipeRightRec.direction = .right
self.view!.addGestureRecognizer(swipeRightRec)

swipeLeftRec.addTarget(self, action: #selector(self.swipedLeft) )
swipeLeftRec.direction = .left
self.view!.addGestureRecognizer(swipeLeftRec)

And then these functions:

@objc func swipedRight() {
    if background.position.x + 250 > maxBackgroundX {
        let moveAction = SKAction.moveTo(x: maxBackgroundX, duration: 0.3)
        background.run(moveAction)
    } else {
        let moveAction = SKAction.moveTo(x: background.position.x + 250, duration: 0.3)
        background.run(moveAction)
    }
}

@objc func swipedLeft() {
    if background.position.x - 250 < minBackgroundX {
        let moveAction = SKAction.moveTo(x: minBackgroundX, duration: 0.3)
        background.run(moveAction)
    } else {
        let moveAction = SKAction.moveTo(x: background.position.x - 250, duration: 0.3)
        background.run(moveAction)
    }
}

Yes this means that the background moves a set amount each time you swipe, no matter how big the swipe is, but it is exactly what I required for my game. I hope this helps someone else who needs the same thing!