Multiple circles drawn SpriteKit - swift

Question

I'm working on simple game which will based on paiting background by player. In left and right corner there will be buttons which will move character to left or right. I've already implemented that (character is moving and lefts painted background behind), but with adding another circles fps's drops really fast. Is there any solution to that?
import SpriteKit
class GameScene: SKScene {
var playerDot:PlayerDot = PlayerDot(imageNamed:"player")
var isTurningLeft:Bool = false
var isTurningRight:Bool = false
var lastLocation:CGPoint = CGPoint()
override func didMoveToView(view: SKView) {
/* Setup your scene here */
let myLabel = SKLabelNode(fontNamed:"Helvetica")
myLabel.name = "left"
myLabel.text = "Left"
myLabel.fontSize = 30
myLabel.horizontalAlignmentMode = .Left
myLabel.position = CGPoint(x:CGRectGetMinX(self.frame), y:CGRectGetMinY(self.frame))
self.addChild(myLabel)
let myLabel2 = SKLabelNode(fontNamed:"Helvetica")
myLabel2.name = "right"
myLabel2.text = "Right"
myLabel2.fontSize = 30
myLabel2.horizontalAlignmentMode = .Right
myLabel2.position = CGPoint(x:CGRectGetMaxX(self.frame), y:CGRectGetMinY(self.frame))
self.addChild(myLabel2)
playerDot.position = CGPoint(x:CGRectGetMaxX(self.frame)/2, y:CGRectGetMinY(self.frame))
self.addChild(playerDot)
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let location = touch.locationInNode(self)
if let theName = self.nodeAtPoint(location).name {
if theName == "left" {
isTurningLeft = true
isTurningRight = false
}
else if theName == "right" {
isTurningRight = true
isTurningLeft = false
}
}
}
}
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let location = touch.locationInNode(self)
if let theName = self.nodeAtPoint(location).name {
if theName == "left" {
isTurningLeft = false
}
else if theName == "right" {
isTurningRight = false
}
}
}
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let location = touch.locationInNode(self)
if let theName = self.nodeAtPoint(location).name {
if theName == "left" {
isTurningLeft = false
}
else if theName == "right" {
isTurningRight = false
}
}
}
}
override func update(currentTime: CFTimeInterval) {
if(isTurningLeft){
playerDot.increaseAngle()
} else if (isTurningRight){
playerDot.decreaseAngle()
}
//calculates new character position based on angle of movement changed
playerDot.updatePosition()
drawCircle()
}
func drawCircle(){
if(distanceFromCGPoints(lastLocation, b: playerDot.position)>2){
let circle = SKShapeNode(circleOfRadius: 10 )
circle.position = playerDot.position
circle.fillColor = SKColor.orangeColor()
circle.strokeColor = SKColor.orangeColor()
self.addChild(circle)
lastLocation = playerDot.position
}
}
func distanceFromCGPoints(a:CGPoint,b:CGPoint)->CGFloat{
return sqrt(pow(a.x-b.x,2)+pow(a.y-b.y,2));
}
func random() -> CGFloat {
return CGFloat(Float(arc4random()) / 0xFFFFFFFF)
}
func random(min min: CGFloat, max: CGFloat) -> CGFloat {
return random() * (max - min) + min
}
}
EDIT:
drawCircle with SKShapeNode replaced with SKSpriteNote
func drawCircle(){
if(distanceFromCGPoints(lastLocation, b: playerDot.position)>2){
let playerDot2 = SKSpriteNode(imageNamed:"player")
playerDot2.position = playerDot.position
self.addChild(playerDot2)
lastLocation = playerDot.position
}
}

Answer 1

If you are having frame rate drops then some parts of your code are slowing down execution too much. You need to optimise your code. Use Instruments (Time Profiler) to find out which lines/functions are causing problems speed wise. If you have never used it before read up on it and use it a couple times to get the gist, then I recommend watching the WWDC video Profiling In-Depth

Answer 2

Based on your edit (switching to SKSpriteNode), this is how you could do it:
Declare a texture as a property of your scene. This way, you load it once and reuse it later:
let yourTexture = SKTextureAtlas(named: "yourAtlas").textureNamed("yourTexture")
Then in your drawCircle method:
func drawCircle(){
if(distanceFromCGPoints(lastLocation, b: playerDot.position)>2){
let playerDot2 = SKSpriteNode(texture: yourTexture)
playerDot2.position = playerDot.position
self.addChild(playerDot2)
lastLocation = playerDot.position
}
}
This way (by using SKSpriteNode instead of SKShapeNode) you have reduced number of draw calls required to render all those circles. Also because you are reusing the same texture, instead of allocating it every time using imageNamed you have reduced greatly an amount of memory that app consumes. Now, SpriteKit can render hundreds of nodes #60 fps if those nodes are rendered in batches. Still there is a limit before fps start dropping. And that depends on a device.