How to change color of SKShapeNode randomly each time spawned? - sprite-kit

Question

Currently, when running this code, a colored ball runs from the top of the screen to the bottom. When it reaches the bottom it respawns at the top and drops again. I need the ball to change to a random color each time it spawns again. I have a colorChange action but it still doesn't change the color of the ball when it runs.
import SpriteKit
class GameScene: SKScene {
let ball = SKShapeNode(circleOfRadius: 20)
let label = SKLabelNode(fontNamed: "Futura")
let colorChange = SKAction.colorizeWithColor(.blueColor(), colorBlendFactor: 1, duration: 1)
let randomRed = Int(arc4random_uniform(255))
let randomGreen = Int(arc4random_uniform(255))
let randomBlue = Int(arc4random_uniform(255))
override func didMoveToView(view: SKView) {
let sceneBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
self.physicsBody = sceneBody
//Ball Transition
let ballTransition = SKAction.sequence([SKAction.fadeInWithDuration(1)])
ball.runAction(ballTransition)
ball.fillColor = UIColor(red: 100, green: 100, blue: 0, alpha: 1)
ball.physicsBody = SKPhysicsBody(circleOfRadius: 25)
ball.physicsBody?.affectedByGravity = false
ball.position = CGPoint(x: self.frame.size.width/2, y: CGFloat(self.frame.size.height*1))
ballMovement()
self.addChild(ball)
self.addChild(label)
}
func ballMovement() {
let moveBall = SKAction.moveToY(0, duration: 3)
let goBackUp = SKAction.moveToY(self.frame.size.height, duration:0)
let keepFalling = SKAction.sequence([moveBall, goBackUp, colorChange])
ball.runAction(SKAction.repeatActionForever(keepFalling))
//Label Sprite
label.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame))
label.fontColor = SKColor.redColor()
label.fontSize = 30
}
override func update(currentTime: CFTimeInterval) {
label.text = "\(ball.position.y)"
if ball.position.y < 26 {
ball.position = CGPoint(x: self.frame.size.width/2, y: CGFloat(self.frame.size.height*1))
}
}
}

Answer 1

Instead of using an SKAction to change the color, just do
ball.color = UIColor...
To generate a random color check this out: How to make a random background color with Swift
and use that to generate a random color
ball.color = .randomColor()

Answer 2

I suggest you don't use an SKShape for an important piece that moves because I find that they can slow down the app and cause problems. I would use an SKSpritenode instead for the ball. If you then make the ball default as all white, you can change the colour by doing this:
ball.colorBlendFactor = 1
ball.color = SKColor(hue: randomNumberFunctionBetweenZeroAndOne(), saturation: 0.75, contrast: 0.5)
The hue should be a random value between 0 and 1.
If you put this inside a function, you could call the function to change the colour of the ball inside and SKAction or anywhere else.