I have an AR game using ARKit with SceneKit that works just fine in iOS 17.
In the iOS 18 betas, the AR background image shows black instead of showing the real world. As a result there's no tracking and obviously the whole game is useless.
I narrowed down the issue to showing the Game Center Access Point.
My app has ViewController 1 (VC1) showing the main menu and that's where I want to show the GC Access Point. From there you open VC2 which shows a list of levels. Selecting any level will open VC3 which has the ARScene.
Following is the code I use to start Game Center in VC1:
GKLocalPlayer.local.authenticateHandler = { gcAuthVC, error in
let isGameCenterReady = (gcAuthVC == nil) && (error == nil)
if let viewController = gcAuthVC {
self.present (viewController, animated: true, completion: nil)
}
if error != nil {
print(error?.localizedDescription ?? "")
}
if isGameCenterReady {
GKAccessPoint.shared.location = .topLeading
GKAccessPoint.shared.showHighlights = true
GKAccessPoint.shared.isActive = true
}
}
When switching to VC2 I run GKAccessPoint.shared.isActive = false so that the Access Point will no longer show in any of the following VCs. I tried running it in VC1, VC2, and again in VC3 - it doesn't change anything. Once I reach VC3, the background is black.
If in VC1 I don't run GKAccessPoint.shared.isActive = true, so I don't activate the access point, the behavior is as follows:
If I wait until after the Game Center login animation completes and closes on its own and then I proceed to VC2 and VC3, the camera image will show correctly
If I quickly move to VC2 before the Game Center login animation has completed, so my code will close it by setting active = false, and then I continue to VC3, I will see the black background problem.
So it does look like activating the access point and then de-activating it causes the issue. BTW, if I activate the access point and leave it on in all VCs, the same black background issue persists.
Other than that, when I'm in VC3 with the black background and I switch to another app (so my game moves to the background), when it returns to the foreground, the camera suddenly shows the real world correctly!
I tried to manually reset the AR session by pausing and restarting it, but that didn't change anything. Also, when I check with the debugger, it looks like when the app comes back to the foreground it also doesn't run the session start code.
But something does seem to reset itself so I wonder what that is. Maybe I could trigger the same manually in my cdoe???
I repeat that everything works just fine in iOS 17 and below. This problem only started with the iOS 18 beta (currently on beta 5, but it started in some of the previous betas as well).
So could this be a bug in iOS 18?
As a workaround I could check the iOS version and if it's iOS18 not activate the access point, hoping that the user will not jump to VC2 too quickly, and show my own button which will open Game Center. But I'd rather give the users the full experience with their own avatar and the highlights showing up. Plus, certainly some users will move quickly to VC2 and that will be an awful experience.
Any help would be greatly appreciated. Thanks!
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I just upgraded my macOS, Xcode and Simulator all to the newest beta version 26.
Then I found two issues when building my app with Xcode 26 and running it on simulator 26.
The game center access point no longer shows up in the app. This is how it's configured in the past. And it still works on simulator 18.4
func authenticatePlayer() {
GKAccessPoint.shared.location = .topTrailing
self.localPlayer.authenticateHandler = { viewController, error in
if let viewController = viewController {
// can present Game Center login screen
} else if self.localPlayer.isAuthenticated {
// game can be started
} else {
// user didn't log in, continue the game without game center
}
}
}
After game ended, the leaderboard won't load. This is how it's implemented in the past. It's still working in simulator 18.4
struct GameCenterView: UIViewControllerRepresentable {
@Environment(\.presentationMode) var presentationMode
...
func makeUIViewController(context: Context) -> GKGameCenterViewController {
let viewController = GKGameCenterViewController(
leaderboardID: getLeaderBoardID(with: leaderBoardGameMode),
playerScope: .global,
timeScope: .allTime
)
viewController.gameCenterDelegate = context.coordinator
return viewController
}
func updateUIViewController(_ uiViewController: GKGameCenterViewController, context: Context) {}
func makeCoordinator() -> Coordinator {
Coordinator(self)
}
class Coordinator: NSObject, GKGameCenterControllerDelegate {
let parent: GameCenterView
init(_ parent: GameCenterView) {
self.parent = parent
}
func gameCenterViewControllerDidFinish(_ gameCenterViewController: GKGameCenterViewController) {
parent.presentationMode.wrappedValue.dismiss()
}
}
}
Hi there,
With a couple of other developers we have been busy with migrating our SpriteKit games and frameworks to Swift 6.
There is one issue we are unable to resolve, and this involves the interaction between SpriteKit and GameplayKit.
There is a very small demo repo created that clearly demonstrates the issue. It can be found here:
https://github.com/AchrafKassioui/GameplayKitExplorer/blob/main/GameplayKitExplorer/Basic.swift
The relevant code also pasted here:
import SwiftUI
import SpriteKit
struct BasicView: View {
var body: some View {
SpriteView(scene: BasicScene())
.ignoresSafeArea()
}
}
#Preview {
BasicView()
}
class BasicScene: SKScene {
override func didMove(to view: SKView) {
size = view.bounds.size
anchorPoint = CGPoint(x: 0.5, y: 0.5)
backgroundColor = .gray
view.isMultipleTouchEnabled = true
let entity = BasicEntity(color: .systemYellow, size: CGSize(width: 100, height: 100))
if let renderComponent = entity.component(ofType: BasicRenderComponent.self) {
addChild(renderComponent.sprite)
}
}
}
@MainActor
class BasicEntity: GKEntity {
init(color: SKColor, size: CGSize) {
super.init()
let renderComponent = BasicRenderComponent(color: color, size: size)
addComponent(renderComponent)
let animationComponent = BasicAnimationComponent()
addComponent(animationComponent)
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
@MainActor
class BasicRenderComponent: GKComponent {
let sprite: SKSpriteNode
init(color: SKColor, size: CGSize) {
self.sprite = SKSpriteNode(texture: nil, color: color, size: size)
super.init()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
class BasicAnimationComponent: GKComponent {
let action1 = SKAction.scale(to: 1.3, duration: 0.07)
let action2 = SKAction.scale(to: 1, duration: 0.15)
override init() {
super.init()
}
override func didAddToEntity() {
if let renderComponent = entity?.component(ofType: BasicRenderComponent.self) {
renderComponent.sprite.run(SKAction.repeatForever(SKAction.sequence([action1, action2])))
}
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
As SKNode is designed to run on the MainActor, the BasicRenderComponent is attributed with MainActor as well. This is needed as this GKComponent is dedicated to encapsulate the node that is rendered to the scene.
There is also a BasicAnimationComponent, this GKComponent is responsible for animating the rendered node.
Obviously, this is just an example, but when using GameplayKit in combination with SpriteKit it is very common that a GKComponent instance manipulates an SKNode referenced from another GKComponent instance, often done via open func update(deltaTime seconds: TimeInterval) or as in this example, inside didAddToEntity.
Now, the problem is that in the above example (but the same goes foupdate(deltaTime seconds: TimeInterval) the methoddidAddToEntity is not isolated to the MainActor, as GKComponent is not either.
This leads to the error Call to main actor-isolated instance method 'run' in a synchronous nonisolated context, as indeed the compiler can not infer that didAddToEntity is isolated to the MainActor.
Marking BasicAnimationComponent as @MainActor does not help, as this isolation is not propogated back to the superclass inherited methods.
In fact, we tried a plethora of other options, but none resolved this issue.
How should we proceed with this? As of now, this is really holding us back migrating to Swift 6. Hope someone is able to help out here!
Hi — we’re testing our app on iOS 26 and ran into strange behavior with GKLocalPlayer.local.authenticateHandler.
GKLocalPlayer.local.authenticateHandler = { [weak self] viewController, error in
// additional code
}
What happens:
When we assign authenticateHandler on iOS 26 and the user is not signed in to Game Center, the system shows a full-screen Game Center overlay asking the user to sign in.
If the user taps Cancel, nothing further happens — the closure is not invoked again, so we don’t receive an error or any callback. The app never learns whether the auth was cancelled or failed.
In previous iOS versions the closure was called (with viewController / error as appropriate) and the flow worked as expected.
What we tried:
Verified authenticateHandler is being set.
Checked GKLocalPlayer.local.isAuthenticated after the overlay dismisses — it’s unchanged.
Observed system logs: a com.apple.GameOverlayUI scene is created and later removed (so the auth overlay is shown by the system).
Confirmed the same code works on earlier iOS versions. :thinking:
Question:
Has anyone seen authenticateHandler not being invoked on iOS 26 when the Game Center auth overlay is presented? Could this be a behavioral change in iOS 26 (overlay runs in a separate system process), or a bug? Any suggested workarounds to reliably detect that the user cancelled the sign-in (for example: listening for willResignActive / didBecomeActive, watching for a system overlay, or saving/presenting the viewController manually)?
Thanks in advance for any advice — we’d appreciate pointers or suggested diagnostics ?