Different sprite position with the same code - ios

Question

I have a weird issue with my sprite position, I tried clean build, restart xcode, and run in different schemes(iPhone5s, iPhone6), they all return the same strange issue.
I tried to set the position of the sprite by:
balls.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) + self.frame.size.width)
so when I println(balls.position) to the console, it returns (0.0, 0.0)
But when I tried
println(CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) + self.frame.size.width)
it returns (512.0,1408.0), and this is correct position where the ball should be.
I'm having issue with the last function, func ballPosition, it is used to determind the position of the sprite "balls". for some reason it is always (0, 0).
Here are the complete code from my test project:
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
var circle = SKShapeNode()
var balls = SKShapeNode()
var ballColor = ["red", "blue", "green", "yellow"]
var points = ["up", "down", "left", "right"]
override func didMoveToView(view: SKView) {
backgroundColor = SKColor.whiteColor()
// set circle position and size
circle = SKShapeNode(circleOfRadius: 100 ) // Size of Circle
circle.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame)) //Middle of Screen
circle.strokeColor = SKColor.whiteColor()
circle.fillColor = SKColor.orangeColor()
self.addChild(circle)
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
/* Called when a touch begins */
circleRotate()
ballPosition()
// test ball position, this is the part with the issue I mentioned above.
println(balls.position) // (0, 0)
println(CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) + self.frame.size.width)) // (512.0,1408.0)
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
}
func circleRotate() {
let circleAction = SKAction.rotateByAngle(CGFloat(-M_PI * 2 / 3), duration: 0.1)
circle.runAction(SKAction.repeatAction(circleAction, count: 1))
}
func ballMove() {
let ballMovement = SKAction.moveTo(CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame)), duration: 5)
balls.runAction(ballMovement)
}
func randomColor() {
let ballColorIndex = Int(arc4random_uniform(UInt32(ballColor.count)))
balls = SKShapeNode(circleOfRadius: 10 )
if ballColorIndex == 0 {
balls.strokeColor = SKColor.whiteColor()
balls.fillColor = SKColor.redColor()
// balls.zPosition = 10
ballMove()
} else if ballColorIndex == 1 {
balls.strokeColor = SKColor.whiteColor()
balls.fillColor = SKColor.blueColor()
// balls.zPosition = 10
ballMove()
} else if ballColorIndex == 2 {
balls.strokeColor = SKColor.whiteColor()
balls.fillColor = SKColor.greenColor()
// balls.zPosition = 10
ballMove()
} else if ballColorIndex == 3 {
balls.strokeColor = SKColor.whiteColor()
balls.fillColor = SKColor.yellowColor()
// balls.zPosition = 10
ballMove()
}
}
func ballPosition() {
let ballPointIndex = Int(arc4random_uniform(UInt32(points.count)))
if ballPointIndex == 0 {
balls.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) + self.frame.size.width)
randomColor()
self.addChild(balls)
} else if ballPointIndex == 1 {
balls.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) - self.frame.size.height)
randomColor()
self.addChild(balls)
} else if ballPointIndex == 2 {
balls.position = CGPoint(x:CGRectGetMidX(self.frame) - self.frame.size.width, y:CGRectGetMidY(self.frame))
randomColor()
self.addChild(balls)
} else if ballPointIndex == 3 {
balls.position = CGPoint(x:CGRectGetMidX(self.frame) + self.frame.size.width, y:CGRectGetMidY(self.frame))
randomColor()
self.addChild(balls)
}
}
}

Answer 1

The problem is you're overwriting ball in randomColor() - you're creating a new node which hasn't been added to the parent view.
The underlying problem is you've structured your code in a way that leads to confusion and mistakes. You should keep your functions single purposed. They should do what they say they do. A function called randomColor() should not move the move the ball or set the ball size. The position function should not set the color.
I rearranged the code and ran it. That bug is fixed. You can see what I changed and should be able to get further now. Good luck.
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate {
var circle = SKShapeNode()
var ball = SKShapeNode(circleOfRadius: 10)
var ballColor = ["red", "blue", "green", "yellow"]
var points = ["up", "dowm", "left", "right"]
override func didMoveToView(view: SKView) {
backgroundColor = SKColor.whiteColor()
circle = SKShapeNode(circleOfRadius: 100 ) // Size of Circle
circle.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame)) //Middle of Screen
circle.strokeColor = SKColor.whiteColor()
circle.fillColor = SKColor.orangeColor()
self.addChild(circle)
self.addChild(ball)
ball.position = CGPointMake(150, 0)
println("Initial Ball Pos: \(ball.position)")
}
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
circleRotate()
setRandomBallPosition()
setRandomColor()
ballMove()
// test ball position
println("--------------")
println("Ball Pos: \(ball.position)")
println("Circle pos: \(circle.position)")
println("Midpoint: \(CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) + self.frame.size.width))")
println("--------------")
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
}
func circleRotate() {
let circleAction = SKAction.rotateByAngle(CGFloat(-M_PI * 2 / 3), duration: 0.1)
circle.runAction(SKAction.repeatAction(circleAction, count: 1))
}
func ballMove() {
let ballMovement = SKAction.moveTo(CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame)), duration: 5)
ball.runAction(ballMovement)
}
func setRandomColor() {
ball.strokeColor = SKColor.whiteColor()
let ballColorIndex = Int(arc4random_uniform(UInt32(ballColor.count)))
switch(ballColorIndex) {
case 0:
ball.fillColor = SKColor.redColor()
case 1:
ball.fillColor = SKColor.blueColor()
case 2:
ball.fillColor = SKColor.greenColor()
case 3:
ball.fillColor = SKColor.yellowColor()
default:
println("Unexpected random index value ", ballColorIndex)
}
}
func setRandomBallPosition() {
let ballPointIndex = Int(arc4random_uniform(UInt32(points.count)))
println("ballPointIndex = \(ballPointIndex)")
switch(ballPointIndex) {
case 0:
ball.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) + (self.frame.size.width / 2))
case 1:
ball.position = CGPoint(x:CGRectGetMidX(self.frame), y:CGRectGetMidY(self.frame) - (self.frame.size.height / 2))
case 2:
ball.position = CGPoint(x:CGRectGetMidX(self.frame) - (self.frame.size.width / 2), y:CGRectGetMidY(self.frame))
case 3:
ball.position = CGPoint(x:CGRectGetMidX(self.frame) + (self.frame.size.width / 2), y:CGRectGetMidY(self.frame))
default:
println("Unexpected random index value: ", ballPointIndex)
}
println("ball position = \(ball.position)")
}
}