Custom SKSpriteNode addChild not working - ios

Question

I am trying to develop a game which need to have a common background across all the scenes using SpriteKit and Swift. Since the background is common and its actions need to be continuous, I created a custom singleton subclass of SKSpriteNode like this:
class BackgroundNode: SKSpriteNode {
static let sharedBackground = BackgroundNode()
private init()
{
let texture = SKTexture(imageNamed: "Background")
super.init(texture: texture, color: UIColor.clearColor(), size: texture.size())
addActors()
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
private func addActors() {
addClouds()
}
private func addClouds() {
addCloud1()
}
private func addCloud1() {
let cloud1 = SKSpriteNode(imageNamed: "Cloud1")
cloud1.size = CGSizeMake(0.41953125*self.size.width, 0.225*self.size.height)
cloud1.position = CGPointMake(-self.size.width/2, 0.7*self.size.height)
self.addChild(cloud1)
let moveAction = SKAction.moveTo(CGPointMake(self.size.width/2, 0.7*self.size.height), duration: 20)
cloud1.runAction(SKAction.repeatActionForever(moveAction))
}
}
And from the GameScene class I am adding this node to the current view like this:
class GameScene: SKScene {
override func didMoveToView(view: SKView) {
BackgroundNode.sharedBackground.size = CGSizeMake(self.size.width, self.size.height)
BackgroundNode.sharedBackground.position = CGPointMake(self.size.width/2, self.size.height/2)
addChild(BackgroundNode.sharedBackground)
}
}
The background image is showing up correctly, but the cloud is not getting added. As of the code above The cloud should appear out of the screen and animate into and then again out of the screen through the other edge, but to verify if it is getting added, I even tried adding the cloud to the center of the screen without any animations. Still the cloud didn't show up. What can be the issue here? And how to fix it?
EDIT
I figured out that the child is actually getting added but is getting added and moving through some points far above the screen. I also figured out that it MIGHT have something to do with anchor point of the cloud, but whatever value I set as anchor point, the cloud always remains on the top right corner of the screen. What can I do about the anchor points to make the clouds appear as it should(considering the lower left corner as (0, 0) is what I want)

Answer 1

Solved the issue. The problem was that I had to manually set the anchor points of the Scene and the node. Setting the anchor point of both the Scene and the node to (0, 0) solved the issue. The new code looks as follows:
GameScene
override func didMoveToView(view: SKView) {
anchorPoint = CGPointMake(0, 0) //Added this
BackgroundNode.sharedBackground.size = CGSizeMake(self.size.width, self.size.height)
BackgroundNode.sharedBackground.position = CGPointMake(0, 0)
addChild(BackgroundNode.sharedBackground)
}
BackgroundNode
private init()
{
let texture = SKTexture(imageNamed: "Background")
super.init(texture: texture, color: UIColor.clearColor(), size: texture.size())
anchorPoint = CGPointMake(0, 0) //Added this
addActors()
}