sprite kit ship turtle

spritekit

import UIKit
import SpriteKit
import XCPlayground

let view = SKView(frame: CGRectMake(0, 0, 300, 300))
let scene = SKScene(size: view.frame.size)
view.presentScene(scene)
let ship = SKSpriteNode(imageNamed: "Spaceship.png")
ship.size = CGSizeMake(25, 25)
scene.addChild(ship)
XCPShowView("ship", view: view)

let midX = CGRectGetMidX(view.frame)
let midY = CGRectGetMidY(view.frame)
let deltaVec = CGVectorMake(midX, midY)

//ship.runAction(SKAction.moveBy(deltaVec, duration: 3))

ship.position = CGPointMake(150, 150)

struct Path {
    let penColor: SKColor
    var penDown = false
    let bezierPath: UIBezierPath = UIBezierPath()
    let sprite: SKSpriteNode
    let moveSpeed = 200
    
    func start() {
        bezierPath.moveToPoint(CGPointZero)
    }
    
    func forward(distance: Double) {
        let headingInRadians = Double(sprite.zRotation)
        
        let dx = distance * cos(headingInRadians)
        let dy = distance * sin(headingInRadians)
        let point = CGPointMake(CGFloat(dx), CGFloat(dy))
        if penDown {
            bezierPath.addLineToPoint(point)
        } else {
            bezierPath.moveToPoint(point)
        }
    }
    
    func turn(angle: CGFloat) {
        sprite.zRotation = angle
    }
    
    func startPen(color: SKColor) {
        
    }
    
    func stopPen() {
        
    }
}

let p = Path(penColor: SKColor.whiteColor(), penDown: true, sprite: ship)

p.start()
p.forward(100)
p.turn(CGFloat(M_PI_4))
p.forward(50)
p.turn(CGFloat(M_PI))
p.forward(50)

let linen = SKShapeNode(path: p.bezierPath.CGPath)
linen.strokeColor = p.penColor
scene.addChild(linen)
linen.position = ship.position

ship.runAction(SKAction.followPath(p.bezierPath.CGPath, asOffset: true, orientToPath: true, duration: 10))