Swift game lags when creating spritenodes - ios

Question

So I have recently uploaded a game to the app store and have been users reporting lags on older devices.
First of all, the game:
It is called "CURVE" (I am not sure if I am allowed to post its name here, but it would help you understand the problem).The idea of the game is that a ball moves up the screen and passes in gaps between walls. Also there are smaller balls that fall down from the main one, thus creating some sort of path.
Now, the lags. They occur in two main moments. First, when the path is created and second, when the player gets through the gaps.
When the player passes through the gaps, he collides with an invisible node. The collsion is noted, the score is updated. The node is then removed and the player proceeds.
I believe the lags occur when swift either creates a SpriteNode or deletes one. Any ideas as to how to deal with this problem?
Here is the code I use when spawning my obstacles - I think it is where the problem is
func createRocks() {
rockHeight = (frame.height * (heightOfRocks))
if gameState != .Dead {
switch spawnCount {
case 10:
levelUp()
case 20:
levelUp()
case 30:
levelUp()
case 40:
levelUp()
case 50:
levelUp()
case 60:
levelUp()
case 70:
levelUp()
case 80:
levelUp()
case 90:
levelUp()
case 100:
levelUp()
case 110:
levelUp()
case 120:
levelUp()
case 130:
levelUp()
case 140:
levelUp()
case 150:
levelUp()
default:
break
}
}
++spawnCount
let leftRock = SKShapeNode(rectOfSize: CGSize(width: (frame.width), height: (rockHeight)), cornerRadius: (cornerRad))
leftRock.fillColor = themeColor
leftRock.strokeColor = themeBorderColor
leftRock.lineWidth = themeBorderWidth
leftRock.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: ((frame.width) + (themeBorderWidth)), height: ((rockHeight) + (themeBorderWidth))))
leftRock.physicsBody?.dynamic = false
let rightRock = SKShapeNode(rectOfSize: CGSize(width: (frame.width), height: (rockHeight)), cornerRadius: (cornerRad))
rightRock.fillColor = themeColor
rightRock.strokeColor = themeBorderColor
rightRock.lineWidth = (themeBorderWidth)
rightRock.physicsBody = SKPhysicsBody(rectangleOfSize: CGSize(width: ((frame.width) + (themeBorderWidth)), height: ((rockHeight) + (themeBorderWidth))))
rightRock.physicsBody?.dynamic = false
leftRock.zPosition = CGFloat(10 + (21 * levelNumber))
rightRock.zPosition = CGFloat(10 + (21 * levelNumber))
// 2
let rockCollision = SKSpriteNode(color: UIColor.clearColor(), size: CGSize(width: (frame.width * 2), height: 32))
rockCollision.physicsBody = SKPhysicsBody(rectangleOfSize: rockCollision.size)
rockCollision.physicsBody?.dynamic = false
rockCollision.name = "scoreDetect"
addChild(leftRock)
addChild(rightRock)
addChild(rockCollision)
// 3
let rockWidth = frame.width
let yPosition = frame.height + leftRock.frame.height
let rockDistance = frame.width * (gapWidth)
let min = Int(((frame.width) * (wallWidth)) - (rockWidth / 2))
let max = Int(((frame.width) * (1.00 - ((wallWidth)))) - rockDistance - (rockWidth / 2))
let rand = min + Int(arc4random_uniform(UInt32(max - min)))
//GKRandomDistribution(lowestValue: min, highestValue: max)
let xPosition = CGFloat(rand)
// 4
leftRock.position = CGPoint(x: xPosition, y: yPosition)
rightRock.position = CGPoint(x: xPosition + rockWidth + rockDistance, y: yPosition)
rockCollision.position = CGPoint(x: xPosition, y: CGRectGetMidY(frame))
rockCollision.position = CGPoint(x: CGRectGetMidX(frame), y: yPosition + (rockCollision.size.height * 2))
let endPosition = frame.height + (leftRock.frame.height * 2)
let moveAction = SKAction.moveByX(0, y: -endPosition, duration: timeOfRockMovement)
let moveSequence = SKAction.sequence([moveAction, SKAction.removeFromParent()])
leftRock.runAction(moveSequence)
rightRock.runAction(moveSequence)
rockCollision.runAction(moveSequence)
}
func initRocks() {
let create = SKAction.runBlock { [unowned self] in
self.createRocks()
}
let wait = SKAction.waitForDuration(rockSpawnWait)
let sequence = SKAction.sequence([create, wait])
let repeatForever = SKAction.repeatActionForever(sequence)
runAction(repeatForever)
}

Answer 1

Your approach sounds very similar to a SpriteKit tutorial I wrote, but I had no lag at all there. SpriteKit is awfully fast, but it's possible your exact conditions are causing problems. Things to check:
1) Are you using texture atlases? These are faster to load than separate images in your bundle.
2) If you're re-using images a lot, can you store them in an SKTexture then load your nodes from there?
3) Are there other things happening, such as sounds playing? The iOS Simulator frequently has a brief lag when it plays its first sound in a game.
4) Is the path that gets created very complicated?