How to flip a SKPriteNode upside down while being generated automatically - swift

Question

I have a SKSpriteNode generated at every 1 second on a floor. Sometime it's over and sometime under it. The SpriteNode is an image and I want it to be flipped upside down when its under the floor. I tried
SKAction.scaleYto(scale, duration: 0.1
But it doesn't work!
Here is the code
func startGeneratingWallsEvery(seconds: NSTimeInterval) {
generationTimer = NSTimer.scheduledTimerWithTimeInterval(seconds, target: self, selector: "generateWall", userInfo: nil, repeats: true)
}
func stopGenerating() {
generationTimer?.invalidate()
}
func generateWall(){
var scale: CGFloat
let wall = ADWall()
let rand = arc4random_uniform(2)
if rand == 0 {
scale = -1.0
} else {
scale = 1.0
}
//let translate1 = SKAction.moveByX(0, y: scale*(wall.size.height), duration: 0.1)
let flip = SKAction.scaleYTo(scale, duration: 0.1)
wall.position.x = size.width/2 + wall.size.width/2
wall.position.y = scale * (kADGroundHeight/2 + wall.size.height/2)
walls.append(wall)
addChild(wall)
runAction(flip)
}
Help me please!!

Answer 1

I can think of a couple of different strategies for causing the sprit to be generated upside down automatically when they are created:
The first strategy is to have two different images at hand, one which is vertically flipped, and one which is not. When the sprite is created, if it spawns below the floor, simply retexture the SKSpriteNode with:
wall.texture = SKTexture(imageNamed:"flipped_image")
You can use that same method to retexture the sprite again should it ever appear above the floor.
Rotate the image. If you want to keep the texturing simple and but a single image for the wall object, another method you could try is to rotate the image by 180 degress, like so:
if belowFloor == true {
zRotation = CGFloat(M_PI)
}
HTH!