Passing variable from UIViewController to SK Scene - ios

Question

I'm making an a game in XCode 7 using Swift 2. I have a variable that I want to pass from the start screen (which is an UIViewController) to the game scene (which is an SKScene). I want the player to select a character in a UIView and play with it in the SKScene. I also want the score that's in the SKScene to show in the game-over screen that's an UIView. I've seen tutorials for passing data between two UIViewControllers and between two SKScenes, but none of them work for this case.
How can I pass a variable from an UIViewController to a SKScene (and vice versa)?

Answer 1

I ran over this same problem yesterday.
Swift 5.2, xcode 12 and targeting iOS 14. Searched high and low. Eventually found the userData attribute of the SKScene.
Note: The app is based on SwiftUI and the SKScene is inside a UIViewRepresentable:
struct SpriteKitContainer: UIViewRepresentable {
typealias UIViewType = SKView
var skScene: SKScene!
#Binding var timerData : ModelProgressTimer
Not that I am passing a binding into the View - this contains a number of data items I wanted to make available to the scene.
I placed code in two places to populate skScene.userData:
func makeUIView(context: Context) -> SKView {
self.skScene.scaleMode = .resizeFill
self.skScene.backgroundColor = .green
debugPrint("setting user data")
self.skScene.userData = [:]
self.skScene.userData!["color"] = UIColor(timerData.flatColorTwo!)
self.skScene.userData!["running"] = timerData.isRunning
self.skScene.userData!["percent"] = timerData.percentComplete
let view = SKView(frame: .zero)
view.preferredFramesPerSecond = 60
// view.showsFPS = true
// view.showsNodeCount = true
view.backgroundColor = .clear
view.allowsTransparency = true
return view
}
func updateUIView(_ view: SKView, context: Context) {
self.skScene.userData = [:]
self.skScene.userData!["running"] = timerData.isRunning
self.skScene.userData!["color"] = UIColor(timerData.flatColorTwo!)
self.skScene.userData!["percent"] = timerData.percentComplete
view.presentScene(context.coordinator.scene)
}
Then, inside the skScene object, I am able to retrieve the userData values:
var item: SKShapeNode! = nil
override func sceneDidLoad() {
let scaleUp = SKAction.scale(by: 2.0, duration: 1.0)
let scaleDown = SKAction.scale(by: 0.5, duration: 1.0)
scaleUp.timingMode = .easeInEaseOut
scaleDown.timingMode = .easeInEaseOut
let sequence = SKAction.sequence([scaleUp,scaleDown])
actionRepeat = SKAction.repeatForever(sequence)
item = SKShapeNode(circleOfRadius: radius)
addChild(item)
}
override func didChangeSize(_ oldSize: CGSize) {
item.fillColor = self.userData!["color"] as! UIColor
item.strokeColor = .clear
let meRunning = self.userData!["running"] as! Bool
if meRunning {
item.run(actionRepeat)
} else {
item.removeAllActions()
}
}
This draws a circle that "pulses" if the "running" boolean is set in the userdata (a Bool value).

Answer 2

If you haven't already found the answer, I did find a way to do this. I was doing something very similar.
In my case I have a UIView that gets called as a pause menu from my scene. I have made the class and variable names a little more ambiguous so they can apply to your situation as well.
class MyView: UIView {
var scene: MyScene!
var button: UIButton!
init(frame: CGRect, scene: MyScene){
super.init(frame: frame)
self.scene = scene
//initialize the button
button.addGestureRecognizer(UITapGestureRecognizer(target: self, action: "buttonTapped"))
}
func buttonTapped(){
self.removeFromSuperview() // this removes my menu from the scene
scene.doTheThing() // this calls the method on my scene
}
Here are the relevant parts of my scene.
class MyScene: SKScene {
func doTheThing(){
//this is a function on the scene. You can pass any variable you want through the function.
}
}
In your situation, it sounds like the first screen is a UIView and the second screen is the SKScene.
You may want to make your SKScene first, pause it, and then add the UIView in front of the Scene. Once the character is selected, you can remove the UIView and add your character into the scene.
I hope that this answers your question. If it doesn't let me know.

Answer 3

From the level select scene:
let scene = GameScene(fileNamed:"GameScene")
scene?.userData = [:]
scene?.userData!["level"] = 21
self.view?.presentScene(scene!)
From within the game scene:
let level = self.userData!["level"] as! Int