Swift SpriteKit SKPhysicsJointPin - swift

Question

I'm trying to implement a rope in Swift SpriteKit and to add physics to it, the position is good for all, but they won't attach, when I hit play they all fall except the first one which is the "holder". Here is my code:
// create rope holder
let chainHolder = SKSpriteNode(imageNamed: "chainHolder")
chainHolder.position.y = self.frame.maxY - chainHolder.size.height
chainHolder.physicsBody = SKPhysicsBody(circleOfRadius: chainHolder.size.width / 2)
chainHolder.physicsBody?.dynamic = false
//chainHolder.physicsBody?.allowsRotation = true
chains.append(chainHolder)
addChild(chainHolder)
// add each of the rope parts
for i in 0...5 {
let chainRing = SKSpriteNode(imageNamed: "chainRing")
let offset = chainRing.size.height * CGFloat(i + 1)
chainRing.position = CGPointMake(chainHolder.position.x, chainHolder.position.y - offset)
chainRing.name = String(i)
chainRing.physicsBody = SKPhysicsBody(rectangleOfSize: chainRing.size)
//chainRing.physicsBody?.allowsRotation = true
chains.append(chainRing)
addChild(chainRing)
}
// set up joints between rope parts
for i in 1...5 {
var nodeA = chains[i - 1]
var nodeB = chains[i]
var joint = SKPhysicsJointPin.jointWithBodyA(nodeA.physicsBody, bodyB: nodeB.physicsBody,
anchor: CGPointMake(CGRectGetMidX(nodeA.frame), CGRectGetMinY(nodeA.frame)))
physicsWorld.addJoint(joint)
}

Answer 1

I found out that the problem was because I was setting the anchor point for the scene in (0.5, 0.5). If I leave it in (0, 0) everything is ok.