swift - How do I detect which SKSpriteNode has been touched

Question

I find a similar question, but I am trying to detect and identify which Sprite the user touch, and I don't know how to do that. This is my variable:

var sprites: [[SKSpriteNode]] = [[SKSpriteNode(imageNamed: "a"), SKSpriteNode(imageNamed: "b")], [SKSpriteNode(imageNamed: "c"),SKSpriteNode(imageNamed: "d")]]

The idea is identify the spriteNode and then replace it for other sprite or change the color, but I don′t know how to do it with this matrix of spriteNodes, I guess the first step it′s identify the sprite.

Answer 1

What you are trying to do (even if I don't see a reason for this) can be accomplished using delegation pattern. Basically, you will tell your delegate (the scene, or whatever you set as a delegate) to do something for you, and you will do that directly from within the button's touchesBegan method. Also, you will pass the button's name to a scene.

To make this happen, first you have to define a protocol called ButtonDelegate. That protocol defines a requirement which states that any conforming class has to implement a method called printButtonsName(_:):

protocol ButtonDelegate:class {

   func printButtonsName(name:String?)
}

This is the method which will be implemented in your GameSceneclass, but called from within button's touchesBegan. Also, this method will be used to pass a button's name to its delegate (scene), so you will always know which button is tapped.

Next thing is button class itself. Button might look like this:

class Button : SKSpriteNode{

    weak var delegate:ButtonDelegate?

    init(name:String){
        super.init(texture: nil, color: .purpleColor(), size: CGSize(width: 50, height: 50))
        self.name = name
        self.userInteractionEnabled = true
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }


    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {

        delegate?.printButtonsName(self.name)
    }  
}

The important thing here is userInteractionEnabled = true, which means that button will accept touches. Another important thing is a delegate property. As already mentioned, buttons will have the scene set as their delegate. Setting a scene as delegate of buttons will be done later when we create some buttons... To make this easier for you, think of a delegate as a worker who works for his boss :) The boss (a button) tells his worker (a scene) to do something for him (to prints his name).

Okay, so lets make sure that scene conforms to a ButtonDelegate protocol...Why is this important? It is important because the worker (scene) must follow the orders of his boss (a button). By conforming to this protocol, the worker is making a contract with his boss where confirming that he knows how to do his job and will follow his orders :)

class GameScene: SKScene, ButtonDelegate {


    override func didMoveToView(view: SKView) {

        let play = Button(name:"play")
        play.delegate = self
        let stop = Button(name:"stop")
        stop.delegate = self

        play.position = CGPoint(x: frame.midX - 50.0, y: frame.midY)
        stop.position = CGPoint(x: frame.midX + 50.0, y: frame.midY)

        addChild(play)
        addChild(stop)
    }

    func printButtonsName(name: String?) {

        if let buttonName = name {
            print("Pressed button : (buttonName) ")
        }

        //Use switch here to take appropriate actions based on button's name (if you like)
    }
}

And that's it. When you tap the play button, the touchesBegan on a button itself will be called, then the button will tell its delegate to print its name using the method defined inside of scene class.