How to keep a 30˚ distance between two lines anchored at a point - swift

Question

I am trying to create two lines that are anchored at a certain point (sprite) and rotate to form a 30 degree angle between them. Below is an image what I want to achieve.
This is what I've done so far:
extension Int {
var degreesToRadians: Double { return Double(self) * .pi / 180 }
}
extension FloatingPoint {
var degreesToRadians: Self { return self * .pi / 180 }
var radiansToDegrees: Self { return self * 180 / .pi }
}
class GameScene: SKScene, SKPhysicsContactDelegate {
var anchorSprite = SKSpriteNode(imageNamed: "anchorSprite")
var armLeft = SKSpriteNode(imageNamed: "lineSprite")
var armRight = SKSpriteNode(imageNamed: "lineSprite")
override func didMove(to view: SKView) {
self.physicsWorld.gravity = CGVector(dx: 0, dy: -1.8)
self.physicsWorld.contactDelegate = self
var tealBg = SKSpriteNode(imageNamed: "tealBg")
tealBg.position = CGPoint(x: frame.midX, y: frame.midY)
tealBg.zPosition = 10
addChild(tealBg)
anchorSprite.position = CGPoint(x: frame.midX, y: frame.midY + frame.midY/2)
anchorSprite.zPosition = 20
anchorSprite.physicsBody = SKPhysicsBody(rectangleOf: anchorSprite.frame.size)
anchorSprite.physicsBody?.categoryBitMask = pinCategory
anchorSprite.physicsBody?.isDynamic = false
addChild(anchorSprite)
armRight.anchorPoint = CGPoint(x: 0.5, y: 1)
armRight.position = anchorSprite.position
armRight.zPosition = 20
armRight.physicsBody = SKPhysicsBody(rectangleOf: armRight.frame.size)
armRight.zRotation = CGFloat(Double(15).degreesToRadians)//CGFloat(Double.pi/6)
armRight.physicsBody!.isDynamic = true
addChild(armRight)
armLeft.anchorPoint = CGPoint(x: 0.5, y: 1)
armLeft.position = anchorSprite.position
armLeft.zPosition = 20
armLeft.physicsBody = SKPhysicsBody(rectangleOf: armRight.frame.size)
armLeft.zRotation = CGFloat(Double(-15).degreesToRadians)//CGFloat(-Double.pi/6)
armLeft.physicsBody!.isDynamic = true
addChild(armLeft)
//Pin joints
var pinAndRightArmJoint = SKPhysicsJointPin.joint(withBodyA: anchorSprite.physicsBody!, bodyB: armRight.physicsBody!, anchor: CGPoint(x: anchorSprite.position.x, y: self.armRight.frame.maxY))
self.physicsWorld.add(pinAndRightArmJoint)
var pinAndLeftArmJoint = SKPhysicsJointPin.joint(withBodyA: anchorSprite.physicsBody!, bodyB: armLeft.physicsBody!, anchor: CGPoint(x: anchorSprite.position.x, y: self.armLeft.frame.maxY))
self.physicsWorld.add(pinAndLeftArmJoint)
}
Below is an image from running the above code (they are close together).
How can I make sure the lines are always 30˚ apart and maintain 30˚ apart even when rotated?

Answer 1

To keep your two lines separated by exactly 30°, you can use an SKPhysicsJointFixed, which is just what it sounds like: it pins two physicsBodies together in a fixed position. Since you already have them positioned the way you want, just add this code where you have the other SKPhysicsJoints to hold them that way:
let fixArms = SKPhysicsJointFixed.joint(withBodyA: armLeft.physicsBody!, bodyB: armRight.physicsBody!, anchor: CGPoint.zero)
self.physicsWorld.add(fixArms)
Result:

Answer 2

If you make the line nodes children of the anchor sprite (instead of the scene), rotating the anchor sprite node will rotate all the lines along with it without doing anything special with physics. You just need to mind the anchor points so that they align properly (i.e. line's anchor at its extremity rather than center)