Endless Runner reposition player for equal difficulty regardless of aspect ratio - ios

Question

I am creating and endless runner for iphones in landscape mode using SpriteKit. I set up the scene as such:
override func viewDidLayoutSubviews() {
let scene = GameScene(size: CGSize(width: 812, height: 375))
let skView = view as! SKView
scene.backgroundColor = UIColor.red
scene.scaleMode = .aspectFill
skView.presentScene(scene)
skView.showsFPS = true
skView.showsNodeCount = true
print("Screen Size: \(GlobalProperties.screenSize.width) x \(GlobalProperties.screenSize.height)")
print("Scene Size: \(scene.size.width) x \(scene.size.height)")
}
I would like to position the player so that there is the same amount of pixels between the edge of the player and the right edge of the screen regardless of aspect ratio. Is this a reasonable practice for maintaining difficulty between devices? I have the layout setup as such:
override func didMove(to view: SKView) {
let player = SKSpriteNode(texture: SKTexture(imageNamed: "CuteMelon"))
player.anchorPoint = CGPoint(x: 0.5, y: 0.5)
player.position = CGPoint(x: frame.width - 600, y: frame.midY)
self.addChild(player)
let rect = SKSpriteNode(color: .orange, size: CGSize(width: 550, height: 200))
rect.anchorPoint = CGPoint(x: 1, y: 0.5)
rect.position = CGPoint(x: frame.width-50, y: frame.height/2)
self.addChild(rect)
}
I added the rectangle to see if in both cases the player was 600 pixels from the right (leaving a 50px gap to ensure it wasnt running off the edge)
The result is as follows:
iPhone XR: https://imgur.com/y6OYHkK which is working as intended
iPhone 8: https://imgur.com/nkrx5By which is not placing the rectangle 50 pixels from the right bound of the frame.
What do I have to do to fix this issue or should I go about solving it a different way entirely? Thank you

Answer 1

Simply figure out the difference between the scene size and the screen size, and shift the camera over by half that distance. The formula abs((sceneWidth - screenWidth * sceneHeight/screenHeight)/2) will get you that. What this does is scale the screen to whatever height the scene is, then subtract the two differences from the width and return half that value.
override func didMove(to view: SKView) {
let widthPadding = abs((self.frame.width - (UIScreen.main.bounds.width * self.frame.height / UIScreen.main.bounds.height )) / 2)
self.camera = self.camera ?? SKCameraNode()
self.camera.position.x += widthPadding
let player = SKSpriteNode(texture: SKTexture(imageNamed: "CuteMelon"))
player.anchorPoint = CGPoint(x: 0.5, y: 0.5)
player.position = CGPoint(x: frame.width - 600, y: frame.midY)
self.addChild(player)
let rect = SKSpriteNode(color: .orange, size: CGSize(width: 550, height: 200))
rect.anchorPoint = CGPoint(x: 1, y: 0.5)
rect.position = CGPoint(x: frame.width-50, y: frame.height/2)
self.addChild(rect)
}