Save state of GameScene through transitions - ios

Question

I want to build an inventory for my SpriteKit game. For this I want to go to another SKScene File which represents my inventory when I press the pause button. My problem is that when I make a transition from my InventoryScene back to my GameScene, the GameScene loads completely new. This is the transition code from my GameScene class:
func loadInventory(){
if !transitionInProgress{
transitionInProgress = true
if let scene = InventoryScene(fileNamed: "Inventory"){
Globals.InventoryGlobals.levelBeforeSwitch = currentLevel
scene.scaleMode = .aspectFill
let transition = SKTransition.push(with: .down, duration: 0.5)
self.view?.presentScene(scene, transition: transition)
}
}
}
With this code I'll go to my InventoryScene.
Now in my InventoryScene I want to go back to my GameScene with this:
func loadLevel(level: String){
if !transitionInProgress{
transitionInProgress = true
if let scene = GameScene(fileNamed: level){
scene.currentLevel = level
scene.scaleMode = .aspectFill
let transition = SKTransition.doorsOpenHorizontal(withDuration: 1)
self.view?.presentScene(scene, transition: transition)
}
}
}
The transitions are working but my problem is that the GameScene loads completely new, which is obviously because I instantiate a new GameScene. So when the player is in the middle of the level and then goes to the Inventory and back to the GameScene, the player is back at the beginning of the level. If I go from the Inventory back to the scene I want to be the GameScene as it was before (player position, enemy health, etc.)
Has anyone an idea how i can do this?

Answer 1

Retaining your scene is very simple, all you need to do is retain the scene with a strong reference
In your ViewController, it is as simple as storing a variable
class ViewController : UIViewController
{
var gameScene = GameScene(fileNamed:"GameScene")
}
Now for as long as your view controller is alive, your scene will be alive.
To access it, you just need to find a way to tell the MenuScene where your view controller is, then present the scene.
class ViewController : UIViewController
{
var gameScene = GameScene(fileNamed:"GameScene")
lazy var skView : SKView = self.view as! SKView
func gotoMenu()
{
let menu = MenuScene(fileNamed"MenuScene")
menu.viewController = self
skView.presentScene(menu)
}
}
class MenuScene : SKScene
{
var viewController : ViewController!
func returnToGame()
{
view.presentScene(viewcontroller.gameScene)
}
}
But, what if you don't want to use custom SKScene classes all the time, use a view controller, or would rather rely on components, why isn't there a convenient way to go back to a scene.
Well my friend, there is, and it is where userData comes into play
class GameScene : SKScene
{
func gotoMenu()
{
let menu = MenuScene(fileNamed:"MenuScene")
menu.userData = menu.userData ?? ["":Any]()
menu.userData["backToScene"] = self
view.presentScene(menu)
}
}
class MenuScene : SKScene
{
func returnToGame()
{
guard let userData = userData, let scene = userData["backToScene"] as? SKScene
view.presentScene(scene)
}
}
Since we are retaining it in the user data, we can now present the old scene anywhere we have access to the menu scene.
userData is also great in transferring inventory, of course I would create a class to manage the inventory, and just pass the reference via userData
Now, to create a menu that overlays the current scene, that is as simple as applying a new node onto your scene.
You can even use a separate SKS file to layout your menu, and overlay it:
class GameScene : SKScene
{
let menu = MenuScene(fileNamed:"MenuScene")
func overlayMenu()
{
scene.addChild(menu) //You probably want to add an SKCameraNode, and add it to the camera instead
}
override func update(currentTime: CFTimeInterval)
{
if menu.parent != nil
{
menu.update(currentTime:currentTime) //do this only when you need to have a constant update call, be sure to include additional functionality like `didFinishUpdate` in the approprate functions when needed
}
}
}
Of course now would be a good time to develop what is called a worldNode, also may be referred to as gameNode
Essentially what this node is, is the node that holds all your game elements.
This allows you to add overlay nodes that can pause your game.
Your scene hierarchy would like like this:
SKScene
--worldNode
----all nodes that belong in the game
--menuNode
----all nodes that belong on the menu
Now at any time, menu can set the worldNode's isPaused state to true, allowing the game to pause and still giving you the ability to interact with the menuNode

Answer 2

I do layover windows all the time in my Spritekit games, and it doesn't have to be as complicated as you are thinking. Here is how you can do it all in Spritekit without leaving the Scene.
Create a new class which is a subclass of SKSpriteNode for your InventoryDialog.
import SpriteKit
protocol InventoryDialogDelegate: class {
func close()
}
class InventoryDialog: SKSpriteNode {
private var closeButton: SKSpriteNode!
weak var delegate: InventoryDialogDelegate?
init(size: CGSize) {
super.init(texture: nil, color: .clear, size: size)
name = "inventoryDialog"
//do some background design work here
let background = SKSpriteNode(color: .white, size: self.size)
background.zPosition = 1
addChild(background)
closeButton = SKSpriteNode(texture: SKTexture(imageNamed: "closeButton"))
closeButton.position = CGPoint(x: self.size.width / 2 - closeButton.size.width / 2, y: self.size.height / 2 - closeButton.size.height / 2)
closeButton.zPosition = 2
addChild(closeButton)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
let touch = touches.first
let touchLocation = touch!.location(in: self)
if closeButton.contains(touchLocation) {
close()
}
}
func close() {
self.delegate?.close()
}
}
inside your GameScene file
class GameScene: SKScene {
var inventoryDialog: InventoryDialog!
var openButton: SKSpriteNode!
override func didMove(to view: SKView) {
openButton = SKSpriteNode(texture: SKTexture(imageNamed: "openButton"))
openButton.position = CGPoint(x: self.size.width / 2 - closeButton.size.width / 2, y: self.size.height / 2 - closeButton.size.height / 2)
openButton.zPosition = 2
addChild(openButton)
}
func displayInventoryDialog() {
backgroundBlocker = SKSpriteNode(imageNamed: "background3")
backgroundBlocker.size = self.size
backgroundBlocker.zPosition = 4999
addChild(backgroundBlocker)
inventoryDialog = InventoryDialog(size: CGSize(width: 500, height: 800))
inventoryDialog.delegate = self
inventoryDialog.zPosition = 5000
addChild(inventoryDialog)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
//pause any action that you don't want running while the dialog is open
gameLayer.isPaused = true
let touch = touches.first
let touchLocation = touch!.location(in: self)
if openButton.contains(touchLocation) {
displayInventoryDialog()
}
}
}
//MARK: - InventoryDialogDelegate Methods
extension GameScene: InventoryDialogDelegate {
func close() {
//at this point you could update any GUI nesc. based on what happened in your dialog
backgroundBlocker.removeFromParent()
inventoryDialog?.removeFromParent()
gameLayer.isPaused = false
}
}

Answer 3

here is exactly what you wanted.
class GameScene: SKScene {
class InventoryManager: UIView {
override init(frame: CGRect) {
super.init(frame: CGRect(x: 0, y: 0, width: 300, height: 200))
//here is where you set up anything you want to display inside the view
self.backgroundColor = UIColor.green
let Button = UIButton()
Button.frame = CGRect(x: 0, y: 0, width: 40, height: 20)
Button.backgroundColor = UIColor.red
let TouchView = UIView()
TouchView.frame = self.frame
Button.center.x = TouchView.center.x
Button.center.y = TouchView.center.y
TouchView.backgroundColor = UIColor.brown
self.addSubview(TouchView)
//make sure you add any objects that you want to the TouchView and not to the self
TouchView.addSubview(Button)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
var InventoryView = InventoryManager()
var Node = SKSpriteNode()
override func didMove(to view: SKView) {
//this keeps the view centered in the screen
InventoryView.center.x = (self.view?.center.x)!
InventoryView.center.y = (self.view?.center.y)!
Node = SKSpriteNode(color: UIColor.blue, size: CGSize(width: 40, height: 40))
Node.position = CGPoint(x: self.frame.size.width / 3, y: self.frame.size.height / 3)
self.addChild(Node)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
for touch in touches {
let location = touch.location(in: self)
if !(self.view?.frame.contains(location))! {
InventoryView.removeFromSuperview()
}
if Node.contains(location) && InventoryView.isDescendant(of: self.view!) {
self.view?.addSubview(InventoryView)
}
}
}
override func update(_ currentTime: TimeInterval) {
// Called before each frame is rendered
}
}
clicking the blue button adds it to the scene again and clicking anywhere else removes it from the scene