Analog Joystick in Playgrounds

Contents.swift

//: A SpriteKit based Playground

import PlaygroundSupport
import SpriteKit

class JoystickNode: SKNode {
    
    private let radius: CGFloat
    private var baseNode: SKNode
    private var stickNode: SKNode
    
    init(radius: CGFloat) {
        self.radius = radius
        self.baseNode = SKShapeNode(circleOfRadius: radius)
        self.stickNode = SKShapeNode(circleOfRadius: radius / 3)
        
        super.init()
        
        addChild(baseNode)
        addChild(stickNode)
        
        isUserInteractionEnabled = true
    }
    
    required public init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        guard let touch = touches.first else { return }
        let location = touch.location(in: self)
        let distance = sqrt(pow(location.x, 2) + pow(location.y, 2)) / radius
        if distance <= 1 {
            stickNode.position = location
        }
    }
    
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        guard let touch = touches.first else { return }
        let location = touch.location(in: self)
        let distance = sqrt(pow(location.x, 2) + pow(location.y, 2)) / radius
        if distance <= 1 {
            stickNode.position = location
        } else {
            stickNode.position = CGPoint(x: location.x / distance, y: location.y / distance)
        }
    }
    
    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
        stickNode.position = CGPoint.zero
    }
    
    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
        stickNode.position = CGPoint.zero
    }
}

class GameScene: SKScene {
    
    override func didMove(to view: SKView) {
        addChild(JoystickNode(radius: 100))
    }
}

let sceneView = SKView(frame: CGRect(x:0 , y:0, width: 640, height: 480))
let scene = GameScene(size: sceneView.frame.size)
scene.scaleMode = .aspectFill
scene.anchorPoint = CGPoint(x: 0.5, y: 0.5)
sceneView.presentScene(scene)

PlaygroundSupport.PlaygroundPage.current.liveView = sceneView