Gamepad.swift

import SpriteKit

enum GamepadButton {
    case Left
    case Right
}

class Gamepad: SKNode {
    private var leftButton: SKSpriteNode!
    private var rightButton: SKSpriteNode!
    private let disabledAlpha: CGFloat = 0.5

    private (set) var movement: GamepadButton?
    
    init(buttonTexture: SKTexture, buttonPadding: CGFloat = 60.0) {
        super.init()
        setupButtons(buttonTexture, padding: buttonPadding)
        userInteractionEnabled = true
    }
    
    private func setupButtons(texture: SKTexture, padding: CGFloat) {
        setupLeftButton(texture, padding: padding)
        setupRight(texture, padding: padding)
    }
    
    private func setupLeftButton(texture: SKTexture, padding: CGFloat) {
        leftButton = SKSpriteNode(texture: texture)
        leftButton.position = CGPointMake(CGRectGetMidX(frame)-padding/2, CGRectGetMidY(frame))
        addChild(leftButton)
    }
    
    private func setupRight(texture: SKTexture, padding: CGFloat) {
        rightButton = SKSpriteNode(texture: texture)
        rightButton.position = CGPointMake(CGRectGetMidX(frame)+padding/2, CGRectGetMidY(frame))
        rightButton.xScale = rightButton.xScale * -1.0
        addChild(rightButton)
    }
    
    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
        guard let touch = touches.first else { return }
        updateMovement(touch)
    }
    
    override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
        guard let touch = touches.first else { return }
        updateMovement(touch)
    }
    
    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
        cancelMovement()
    }
    
    override func touchesCancelled(touches: Set<UITouch>?, withEvent event: UIEvent?) {
        cancelMovement()
    }
    
    private func updateMovement(touch: UITouch) {
        let touchingNode = nodeAtPoint(touch.locationInNode(self))
        if touchingNode == rightButton {
            movement = .Right
            touchingNode.alpha = 1.0
            leftButton.alpha = disabledAlpha
        }
        else if touchingNode == leftButton {
            movement = .Left
            touchingNode.alpha = 1.0
            rightButton.alpha = disabledAlpha
        }
        else {
            movement = nil
            leftButton.alpha = disabledAlpha
            rightButton.alpha = disabledAlpha
        }
    }
    
    private func cancelMovement() {
        movement = nil
        leftButton.alpha = disabledAlpha
        rightButton.alpha = disabledAlpha
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}