Up and down movement in sprite kit and swift? - swift

Question

Right now, I am creating a new game that will involve a ball that moves up and down the screen by itself without touching a button or the screen. I have been looking everywhere for a solution, but I haven't found one. I know how to make the ball move up and down in objective-c, but not in swift or spritekit. I don't know if the following code will help or not. Any solution is accepted.
class GamePlayScene: SKScene, SKPhysicsContactDelegate {
var ball = SKSpriteNode(imageNamed: "green ball.png")
override func didMoveToView(view: SKView) {
//setup scene
physicsWorld.gravity = CGVector.zeroVector
self.scene?.backgroundColor = UIColor.blackColor()
self.scene?.size = CGSize(width: 640, height: 1136)
ball.position = CGPoint (x: self.size.width * 0.5, y: self.size.width * 0.9)
ball.size = CGSize (width: 80, height: 82)
let moveBallUp = SKAction.moveToY(600, duration: 0.4)
let moveBallDown = SKAction.moveToY(293, duration: 0.4)
self.addChild(ball)
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
let moveBallUp = SKAction.moveToY(600, duration: 0.4)
let moveBallDown = SKAction.moveToY(293, duration: 0.4)
if ball.position.y == 600 {
self.ball.runAction(moveBallUp)
} else {
self.ball.runAction(moveBallDown)
}
}
}

Answer 1

I suggest you use repeatActionForever. If you start your ball position from the bottom of the screen this sequence should work. If you want to start the ball from the top then switch the positions of the actions in moveUpAndDown with each other.
func moveSprite() {
let moveBallUp = SKAction.moveToY(600, duration: 0.4)
let moveBallDown = SKAction.moveToY(293, duration: 0.4)
let moveUpAndDown = SKAction.sequence([moveBallUp, moveBallDown])
let moveUpAndDownForever = SKAction.repeatActionForever(moveUpAndDown)
ball.runAction(moveUpAndDownForever)
}