Why I can't animate the SCNnode on eulerAngle using CAKeyframeAnimation - swift

Question

I'm try to animate an SCNnode using CAKeyframeAnimation, I been able to change the position of my object without problem but I can't animate the change of EulerAngle property.
The following code change the position of the node.
func animatePlaneKey(nodeToAnimate: SCNNode){
let pos = nodeToAnimate.position
let animation = CAKeyframeAnimation(keyPath: "position")
let pos1 = SCNVector3(pos.x, pos.y, pos.z)
let pos2 = SCNVector3(pos.x + 1 , pos.y, pos.z)
let pos3 = SCNVector3(pos.x + 1 , pos.y, pos.z + 1)
animation.values = [pos1,pos2, pos3]
animation.keyTimes = [0,0.5,1]
animation.calculationMode = .linear
animation.duration = 10
animation.repeatCount = 1
animation.isAdditive = true
nodeToAnimate.addAnimation(animation, forKey: "position")
}
and the following one should change the eulerAngles property but does't work.
any idea why I can't animate the rotation?
func animatePlaneKey(nodeToAnimate: SCNNode){
let animation2 = CAKeyframeAnimation(keyPath: "rotation")
let angles = nodeToAnimate.eulerAngles
let rot0 = SCNVector3(angles.x, angles.y, angles.z)
let rot1 = SCNVector3(angles.x, angles.y + Float(deg2rad(45)) , angles.z)
animation2.values = [rot0, rot1]
animation2.keyTimes = [0, 1]
animation2.duration = 2
animation2.repeatCount = .infinity
animation2.isAdditive = true
nodeToAnimate.addAnimation(animation2, forKey: "rotation")
}
Thanks for the help.

Answer 1

You have to use SCNVector4 type (a.k.a. Quaternion) instead of SCNVector3 type (a.k.a. Euler).
And a key "spin around" instead of "rotation".
let ship = scene.rootNode.childNode(withName: "ship", recursively: true)!
let animation = CABasicAnimation(keyPath: "rotation")
let start = SCNVector4(0, 0, 0, 0)
let end = SCNVector4(0, 1, 0, CGFloat(Float.pi * 6))
animation.fromValue = start
animation.toValue = end
animation.duration = 10
animation.repeatCount = .infinity
ship.addAnimation(animation, forKey: "spin around")