Draw straight line in Swift with Sprite Kit, creating multiple lines - ios

Question

I'm trying to make a game in iOS, using Swift and Sprite Kit. I have the following bit of codes, but it's creating multiple lines. What I want to do is to create a single line, end of which will follow the tip of the finger of the user as the user drags the finger across the screen until the he or she takes the finger off the screen, then for the line to remain there. I found a similar question on stack overflow at Drawing straight line with spritekit and UITouch creates multiple lines, but it is written in Objective-C. And I don't think I understood the answer entirely to be honest. I'm using Xcode 7 and Swift 2.
import SpriteKit
class GameScene: SKScene {
override func didMoveToView(view: SKView) {
}
let path = CGPathCreateMutable()
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
let touch = touches.first
let position1 = touch!.locationInNode(self)
CGPathMoveToPoint(path, nil, position1.x, position1.y)
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
let touch = touches.first
let position2 = touch!.locationInNode(self)
CGPathAddLineToPoint(path, nil, position2.x, position2.y)
CGPathCloseSubpath(path)
let line = SKShapeNode()
line.path = path
line.strokeColor = UIColor.blackColor()
line.lineWidth = 5
self.addChild(line)
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
}
}
Any thoughts or suggestions would be greatly appreciated. Thanks.
Ryan

Answer 1

I may be wrong because I don't know too much about game development with Swift. But it appears you are creating a line every time you more your finger, have you tried creating the line in touchesEnded?

Answer 2

Did you try your code without the line
CGPathCloseSubpath(path)
According to the documentation, this is what it does:
Appends a line from the current point to the starting point of the
current subpath and ends the subpath.
and I don't think you want to have an additional line from your last touch to the start of the line with every new touch. Closing of a CGPath is only needed if you want a line that ends where it started.

Answer 3

I would cheat to do this:
Create a very thin sprite, in the line colour you want, and stretch its end point to where you want it to go.
This is effectively a rectangular box made out of an SKSpriteNode that's stretched from the origin to the current point of touch.
Rotating and then stretching a SKSpriteKit node is best done (for me) by attaching it to an SKNode, and rotating the node as needed, then stretching the nested SKSpriteNode as far as is needed to reach the user's current touch point.
Put the origin of the SKNode and the SKSpriteNode, at the same place, the middle left edge, and rotate around that. Or whatever works for you mathematically... This is makes the most sense to me, but it could be the centre points of any edge of the rectangle and you then stretch accordingly.