Touch Sprite, make it jump up then fall down again(repeat as many times as spritenode is tapped.) - swift

Question

I created a project where I have a ball and when the view loads, it falls down, which is good. I'm trying to get the ball to jump back up and fall down again when the Spritenode is tapped.
--This Question was edited--
Originally, I was able to get it to work when sprite.userInteractionEnabled = false. I had to turn this statement true in order to get the score to change.
Now I can't get the balls to fall and be tapped to jump. When I turn ball.physicsBody?.dynamic = true, the balls will fall due to gravity. How do I tap the sprite itself and make it jump.
GameScene.swift (For those who want to try the code for themselves.)
import SpriteKit
class GameScene: SKScene {
var ball: Ball!
private var score = 0 {
didSet { scoreLabel.text = "\(score)" }
}
override func didMoveToView(view: SKView) {
let ball = Ball()
scoreLabel = SKLabelNode(fontNamed:"Geared-Slab")
scoreLabel.fontColor = UIColor.blackColor()
scoreLabel.position = CGPoint( x: self.frame.midX, y: 3 * self.frame.size.height / 4 )
scoreLabel.fontSize = 100.0
scoreLabel.zPosition = 100
scoreLabel.text = String(score)
self.addChild(scoreLabel)
ball.position = CGPoint(x:self.size.width / 2.0, y: 440)
addChild(ball)
ball.physicsBody = SKPhysicsBody(circleOfRadius: 120)
ball.physicsBody?.dynamic = true
ball.physicsBody?.allowsRotation = false
ball.physicsBody?.restitution = 3
ball.physicsBody?.friction = 0
ball.physicsBody?.angularDamping = 0
ball.physicsBody?.linearDamping = 0
ball.physicsBody?.usesPreciseCollisionDetection = true
}
class Ball: SKSpriteNode {
init() {
let texture = SKTexture(imageNamed: "Ball")
super.init(texture: texture, color: .clearColor(), size: texture.size())
userInteractionEnabled = true
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
let scene = self.scene as! GameScene
scene.score += 1
}
Before, it was a SKNode being tapped using CGVectorMake(impulse, velocity) now, it's a SKSpriteNode, and I tried using SKAction, but it either does not work, or I'm putting it in the wrong place(touches begin).

Answer 1

I tested your code and it seems that using firstBall.userInteractionEnabled = true is the cause. Without it, it should work. I did some research (here for example), but can't figure out what's the reason of this behavior with userInteractionEnabled. Or for what reason do you use userInteractionEnabled?
Update due to update of question
First ball.physicsBody?.restitution = 3 defines the bounciness of the physics body. The default value is 0.2 and the property must be between 0.0 ans 1.0. So if you set it to 3.0 it will cause some unexpected effects. I just deleted it to use the default value of 0.2.
Second, to make the ball jump after tap and increase the score I put
physicsBody?.velocity = CGVectorMake(0, 600)
physicsBody?.applyImpulse(CGVectorMake(0, 1100))
in the touchesBegan method of the Ball class
Result