Losing reference to GameViewController from inside SpriteKit when moving between scenes - want to move between SKScene and UITableView - swift

Question

I have a simple (multi scene) spritekit game and would like to implement and display a settings screen using a UITableViewContoller. I am close but keep losing my reference to the games view controller when i change scene, which means i can only segue to the UITableViewController on the first scene when my game starts. I'm hoping someone can help. I setup the UITableView in the storyboard and setup a segue to the tableview from my GameViewController in there.
I have the following set up in my GameViewController file:
override func viewDidLoad() {
super.viewDidLoad()
if let view = self.view as! SKView? {
// Load the SKScene
if let scene = SKScene(fileNamed: "MenuScene") {
// Set the scale mode to scale to fit the window
scene.scaleMode = .aspectFill
//I'VE ADDED THIS
if let gameScene = scene as? MenuScene {
gameScene.viewController = self
}
// Present the scene
view.presentScene(scene)
}
view.ignoresSiblingOrder = true
}
}
func showSettings() {
performSegue(withIdentifier: "openSettings", sender: self)
}
which gives me a reference to the GameViewController from my SKScene. I then load the UITableViewController from my SKScene in spritekit when a user touches an SKLabelNode. A simpler version of my MenuScene code looks something like this:
class MenuScene: SKScene {
var viewController: GameViewController?
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?)
{
let touch:UITouch = touches.first!
let positionInScene = touch.location(in: self)
let touchedNode = self.atPoint(positionInScene)
if let name = touchedNode.name
{
let transition:SKTransition = SKTransition.fade(withDuration: 0.75)
var scene:SKScene = SKScene()
if (name == "settingsBTN"){
viewController?.showSettings()
}
else if (name == "randomBTN"){
scene = StarScene(size: self.size)
scene.backgroundColor = SKColor.black
self.view?.presentScene(scene, transition: transition)
}
}
}
}//end of MenuScene
The table view is presented fine when i tap the settingsBTN when first starting the game. however, if i visit another scene in my game (e.g. by pressing randomBTN) and return back to the menu scene i can no longer segue to the Settings view as i have lost the reference to the viewcontroller (it shows as nil) so i can't call the showSettings method in the GameViewController that performs the segue (presumably because i set up the reference to the view controller in the view controller itself).
I can't figure out how to maintain the reference to my GameViewController so i can present the settings screen at any point. Please could someone help.

Answer 1

There are two simple methods to call a GameViewController function from other classes: through a delegate or by making the class instance static.
// DELEGATE
//
// GameViewController.swift
protocol GameView_Delegate
{
func show_ui()
}
class GameViewController: UIViewController, GameView_Delegate
{
override func viewDidLoad()
{
// ...
if let view = self.view as! SKView?
{
if let scene = SKScene(fileNamed: "MenuScene")
{
scene.scaleMode = .aspectFill
// pass GameViewController reference
scene.gv_delegate = self
}
view.presentScene(scene)
}
// ...
}
func show_ui()
{
// show ui
// ...
}
}
// MenuScene.swift
class MenuScene: SKScene
{
var gv_delegate : GameView_Delegate!
func settings()
{
// call function show_ui from GameViewController
gv_delegate.show_ui()
}
func game_scene()
{
let transition = SKTransition.fade(with: UIColor.white, duration: 1.0)
let next_scene = GameScene()
next_scene.anchorPoint = CGPoint(x: 0.5, y: 0.5)
next_scene.scaleMode = self.scaleMode
next_scene.size = self.size
// before moving to next scene, we must pass the delegate, so we
// don't lose the connection with the GameViewController
next_scene.gv_delegate = gv_delegate
self.view?.presentScene(next_scene, transition: transition)
}
}
// GameScene.swift
class GameScene: SKScene
{
var gv_delegate : GameView_Delegate!
func settings()
{
// call function show_ui from GameViewController
gv_delegate.show_ui()
}
func main_scene()
{
let transition = SKTransition.fade(with: UIColor.white, duration: 1.0)
let next_scene = MainScene()
next_scene.anchorPoint = CGPoint(x: 0.5, y: 0.5)
next_scene.scaleMode = self.scaleMode
next_scene.size = self.size
// before moving to next scene, we must pass the delegate, so we
// don't lose the connection with the GameViewController
next_scene.gv_delegate = gv_delegate
self.view?.presentScene(next_scene, transition: transition)
}
}
When you enter a new scene, for example GameScene, the old scene MainScene in our case is deallocated (all variables emptied, all references destroyed) and a new GameScene instance is created and displayed on screen. If afterwards you want to exit that scene and enter MainScene, a new instance of that class will be created with the GameViewController reference empty. We should reference it again or pass the reference before exiting the scene (as in my example).
// STATIC
//
// GameViewController.swift
class GameViewController: UIViewController
{
static var shared : GameViewController!
override func viewDidLoad()
{
super.viewDidLoad()
GameViewController.shared = self
// ...
}
func show_ui()
{
// show ui
// ...
}
}
// MenuScene.swift
class MenuScene: SKScene
{
func settings()
{
// call function show_ui from GameViewController
GameViewController.shared.show_ui()
}
}
Read pros/cons of each method and chose the one that suits your app the best. Also, avoid using UIKit inside SpriteKit.