Different results between iOS 7.1 and 8 while using Swift - ios

Question

I am practicing swift by writing a simple game. However, I noticed something weird happening. I am getting different results when I run my app on iOS 7.1 compared to iOS 8. I am trying to downcast an SKNode to a custom class that I wrote called CircleNode, which inherits from SKSpriteNode. Here is the class:
import UIKit
import SpriteKit
class CircleNode: SKSpriteNode {
var _hasMoved = false
var _touchingCircles:NSMutableArray = NSMutableArray()
var _isTouchingObject = false
var _selectedForDeletion = false
var _isBeingTouched = false
var _xOffset:CGFloat = 0
var _yOffset:CGFloat = 0
func addTouchingCircle(touchingCircle:CircleNode) {
_touchingCircles.addObject(touchingCircle)
_isTouchingObject = true
}
func removeAllCircles(){
self._selectedForDeletion = true
for circ :CircleNode! in _touchingCircles {
if circ._selectedForDeletion == false {
circ.removeAllCircles()
}
}
self.removeFromParent()
}
}
The code that is resulting in weird results is :
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
/* Called when a touch begins */
for touch: AnyObject in touches {
let locationInScene = touch.locationInNode(self)
var selectedNode = self.nodeAtPoint(locationInScene)
let node = selectedNode as? CircleNode
if node {
println("NODE FOUND:circle")
} else {
println("NULL")
}
}
}
In iOS 8, when I click on one of the on screen circles, it prints "NODE FOUND:circle". However, when I do the same on iOS 7.1 it prints "NULL". I have been trying to figure out why this is happening for days, but I can't seem to figure it out. It seems like in iOS 8, var selectedNode = self.nodeAtPoint(locationInScene) actually returns my CircleNode, but in iOS 7.1, it doesn't recognize the node. Any help? Thanks in advance!

Answer 1

There seems to be an issue with the way the XCode templates have changed between XCode 6.0 and 6.1 that causes problems when working with SpriteKit scenes in Swift.
The problem is actually with the initialization of the SKScene from your controller, not the node itself: XCode 6.1 implements the 'unarchiveFromFile' extension method which doesn't appear to work well with Swift on iOS7.1
I got round this by using the following extension:
import UIKit
import SpriteKit
extension SKNode {
class func unarchiveFromFile<T: SKScene>(file : NSString) -> T {
let path = NSBundle.mainBundle().pathForResource(file, ofType: "sks")
var sceneData = NSData(contentsOfFile: path!, options: .DataReadingMappedIfSafe, error: nil)
var archiver = NSKeyedUnarchiver(forReadingWithData: sceneData!)
archiver.setClass(self.classForKeyedUnarchiver(), forClassName: "SKScene")
let scene = archiver.decodeObjectForKey(NSKeyedArchiveRootObjectKey) as T
archiver.finishDecoding()
return scene
}
class func safeInit<T: SKScene>(size: CGSize, _ skFile: NSString) -> T {
let currentVersion = UIDevice.currentDevice().systemVersion
let isIOS8 = currentVersion.compare("8.0", options: NSStringCompareOptions.NumericSearch) != NSComparisonResult.OrderedAscending
if isIOS8 {
let scene = T.unarchiveFromFile(skFile)
scene.size = size
return scene as T
} else {
return T(size: size)
}
}
}
And then calling this from your controller using the following code:
let skView = self.view as SKView
let scene = GameScene.safeInit(skView.bounds.size, "GameScene") as GameScene
That seems to work for me. It feels like a bit of a hack but I can't see any alternative option that actually works.