CALayer 'loses' values set from outside class during implicit animation - animation

Question

I have a CLLayer with an implicit animation on a custom property in Swift.
From inside the class I have access to the interpolated values of my property during the animation. But when I use other properties that I set from outside the class, they don't have a value during the animation. When the animation has ended there original value is available again.
So in the following example people has five random values which are printed to the console in drawInContext, but when the animation is running people is empty
This is my custom CALayer
class BackgroundLayer: CALayer {
#NSManaged var range: Double
var people: []
override class func needsDisplayForKey(key: String) -> Bool {
if key == "range" {
return true
}
return super.needsDisplayForKey(key)
}
override func drawInContext(ctx: CGContext!) {
let center = CGPoint(x: Double(bounds.width)/2, y: Double(bounds.height)-bottomOffset)
let xDist = Double(bounds.width)
let yDist = Double(bounds.height)-bottomOffset-minRadius
let maxDistance = sqrt(pow(xDist,2) + pow(yDist,2))
let radius = CGFloat(minRadius + range * maxDistance)
CGContextSetFillColorWithColor(ctx, UIColor(red: 208/255, green: 2/255, blue: 27/255, alpha: 1).CGColor)
CGContextFillEllipseInRect(ctx, CGRectMake(center.x-radius, center.y-radius, radius*2, radius*2))
println("are there people? \(people)")
}
override func actionForKey(event: String!) -> CAAction! {
if event == "range" {
var currentValue = self.presentationLayer().valueForKey(event) as Double
if currentValue == 0 {
currentValue = self.range
}
var rangeAnim = CABasicAnimation(keyPath: event)
rangeAnim?.fromValue = currentValue
rangeAnim?.duration = 0.5
return rangeAnim
}
return super.actionForKey(event)
}
}
And this is how I use it in my UIViewController that sets the five random values
class ViewController: UIViewController {
private let backgroundLayer = BackgroundLayer()
override func viewDidLoad() {
super.viewDidLoad()
for index in 0..<5 {
println()
let point = (x: Double(arc4random_uniform(UInt32(view.frame.width))), y: Double(arc4random_uniform(UInt32(view.frame.height))))
backgroundLayer.people.append(point)
}
println(backgroundLayer.people)
}
override func viewWillLayoutSubviews() {
backgroundLayer.contentsScale = UIScreen.mainScreen().scale
backgroundLayer.frame = self.view.frame
self.view.layer.addSublayer(backgroundLayer)
backgroundLayer.setNeedsDisplay()
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
backgroundLayer.range = 1
}
override func touchesEnded(touches: NSSet, withEvent event: UIEvent) {
backgroundLayer.range = 0
}
}