Understanding the SKReferenceNode Issue in iOS 11

Introduction

In this article, we will delve into the issues surrounding the SKReferenceNode class in SpriteKit, specifically with regards to its behavior in iOS 11. We’ll explore the code snippet provided by the user and analyze the problem at hand, highlighting potential causes and solutions.

Background on SKReferenceNode

For those unfamiliar with SKReferenceNode, it’s a type of node in SpriteKit that allows for the loading and management of external assets (such as images or 3D models) within your app. This can be particularly useful when working with complex scene hierarchies or when multiple scenes need to share certain assets.

The SKReferenceNode class acts as a proxy for these external assets, providing a way to reference them from within the game logic without having to load them directly into memory. However, this also means that the asset itself is not actually loaded; instead, the node contains metadata about where to find the asset (such as its file path or URL).

The Issue with iOS 11

As mentioned in the original question, users have reported issues with the SKReferenceNode class in iOS 11. Specifically, when running an app on an iOS 11 simulator or device, certain assets that were previously loaded without issue begin to behave erratically.

In this case, we’re dealing with a scene overlay that contains multiple nodes, including a score bar and header node. When the user taps on the screen, the score bar should expand by scaling up its x-position using an SKAction. However, in iOS 11, the score bar fails to appear or expand at all.

Debugging the Issue

To gain insight into what might be causing this issue, we can examine the code snippet provided. Here’s a breakdown of what’s happening:

let path = Bundle.main.path(forResource: "SceneOverlay", ofType: "sks")
let overlay = SKReferenceNode(url: URL(fileURLWithPath: path!))

In this code, we’re using SKReferenceNode to load an external asset (the scene overlay file) from the app’s bundle. The url parameter specifies the location of the asset on disk.

self.addChild(overlay)
overlayNode = overlay.children.first
header = overlayNode!.childNode(withName: "header") as! SKSpriteNode
scoreBar = SKSpriteNode(imageNamed: "redBar")

Here, we’re adding the loaded SKReferenceNode to our scene hierarchy and retrieving its child nodes (in this case, just the header node). We then create a new score bar node and add it to the header node.

scoreBar?.position = CGPoint(x: 0, y: 0)
scoreBar?.zPosition = 10
scoreBar?.anchorPoint = CGPoint(x: 0, y: 0.5)
scoreBar?.xScale = 0
header.addChild(scoreBar!)

In this code, we’re positioning the score bar node correctly and setting its z-position to ensure it appears behind other nodes in the scene.

Solution

The solution to this issue lies in modifying the myScene.isPaused property after transitioning to the new game scene. As noted in the original question:

After transitioning to the scene run myScene.isPaused = false

By setting isPaused to false, we ensure that the game scene is not paused during transition, which should resolve the issue.

It’s worth noting that this solution may have unintended consequences when running on iOS 10 or earlier devices. Therefore, it’s essential to carefully consider the implications of using this workaround in your app.

Conclusion

In conclusion, we’ve explored the issues surrounding SKReferenceNode in iOS 11 and proposed a potential solution. By setting myScene.isPaused to false after transitioning to the new game scene, we can resolve the issue with the score bar failing to appear or expand on iOS 11 devices.

However, as with any technical issue, it’s crucial to consider the broader implications of this workaround and ensure that your app behaves correctly in all supported environments.

Last modified on 2023-10-21