How do I detect if an SKSpriteNode has been touched

I am trying to detect if my sprite node has been touched and I have no idea where to start.

let Pineapple = SKSpriteNode(imageNamed: "Pineappleimg")
Pineapple.userInteractionEnabled = true
Pineapple.position = CGPoint(x: CGRectGetMidX(self.frame) - 200, y: CGRectGetMidY(self.frame));
self.addChild(Pineapple)

First set the name property of the SKSpriteNode to a string.

pineapple.name = "pineapple"
pineapple.userInteractionEnabled = false

then in touchesBegan function in the Scene

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    let touch:UITouch = touches.anyObject()! as UITouch
    let positionInScene = touch.locationInNode(self)
    let touchedNode = self.nodeAtPoint(positionInScene)

    if let name = touchedNode.name
    {
        if name == "pineapple"
        {
            print("Touched")
        }
    }

}

This is one way to do it.
You can also subclass SKSpriteNode and override the touchesBegan inside it.

class TouchableSpriteNode : SKSpriteNode
{
    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        print("touched")
    }
}

Then do

let pineapple = TouchableSpriteNode(imageNamed: "Pineappleimg")
pineapple.userInteractionEnabled = true
pineapple.position = CGPoint(x: CGRectGetMidX(self.frame) - 200, y: CGRectGetMidY(self.frame));
self.addChild(pineapple)