Adding nodes through update method - ios

Question

I awant to add SKSpriteNode's after something repositioned therefore I want to add the nodes through the update method in Swift Sprite Kit.
There are Objects ( platforms ) that move downwards the y axis, once they are out of screen they appear on the top side again ( like an infinite loop ). I visualize this in the update method. Note that the platforms dont really move, rather then I centered a camera on my Player node that moves up.
After the reposition of the platform node, I want to add an Enemy again on top of the platforms, however because I try it through the update method, it adds sometimes more than 1 node on top of it.
I cant reposition the Enemy like I do with the platforms, because it should be a random enemy node.
Any way to call the SpawnEnemy method in the update method, and check if it was called only once?
My Code:
override func didMoveToView(view: SKView) {
/* Setup your scene here */
self.World = SKNode()
self.World.name = "World"
addChild(World)
self.WorldCamera = SKNode()
self.WorldCamera.name = "Camera"
self.World.addChild(WorldCamera)
....
SpawnPlatforms()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform2.position.y + 30))
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform3.position.y + 30))
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform4.position.y + 30))
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform5.position.y + 30))
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform6.position.y + 30))
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform7.position.y + 30))
}
func SpawnPlatforms() {
Platform0 = SKSpriteNode (color: SKColor.greenColor(), size: CGSize(width: self.frame.size.width * 2 , height: 25))
Platform0.position = CGPoint(x: self.frame.size.width / 2, y: -36)
Platform0.zPosition = 1
Platform0.physicsBody = SKPhysicsBody(rectangleOfSize:Platform0.size)
Platform0.physicsBody?.dynamic = false
Platform0.physicsBody?.allowsRotation = false
Platform0.physicsBody?.restitution = 0.0
Platform0.physicsBody?.usesPreciseCollisionDetection = true
Platform0.physicsBody?.velocity = CGVectorMake(0, 0)
Platform0.physicsBody?.categoryBitMask = Platform0Category
Platform0.physicsBody?.collisionBitMask = PlayerCategory | EnemyCategory
Platform0.physicsBody?.contactTestBitMask = PlayerCategory | EnemyCategory
World.addChild(Platform0)
Platform1 = SKSpriteNode (color: SKColor.redColor(), size: CGSize(width: self.frame.size.width * 2 , height: 25))
Platform1.position = CGPoint(x: self.frame.size.width / 2, y: Platform0.position.y + self.frame.size.height / 4.5)
Platform1.zPosition = 1
Platform1.physicsBody = SKPhysicsBody(rectangleOfSize:Platform1.size)
Platform1.physicsBody?.dynamic = false
Platform1.physicsBody?.allowsRotation = false
Platform1.physicsBody?.restitution = 0
Platform1.physicsBody?.usesPreciseCollisionDetection = true
Platform1.physicsBody?.categoryBitMask = Platform1Category
Platform1.physicsBody?.collisionBitMask = PlayerCategory | EnemyCategory
Platform1.physicsBody?.contactTestBitMask = PlayerCategory | EnemyCategory
World.addChild(Platform1)
....a.s.o. for the other 6 platform nodes
}
func SpawnEnemy(position: CGPoint!){
let random = arc4random_uniform(4)
switch (random) {
case 0:
let node1 = SpawnNode1(position)
self.addChild(node1)
break
case 1:
let node2 = SpawnNode2(position)
self.addChild(node2)
break
case 2:
let node3 = SpawnNode3(position)
self.addChild(node3)
break
case 3:
break
default:
break
}
}
override func didSimulatePhysics() {
WorldCamera.position = CGPoint(x: Player.position.x, y: Player.position.y)
self.centerOnNode(WorldCamera!)
}
func centerOnNode(node: SKNode) {
let cameraPositionInScene: CGPoint = WorldCamera.scene!.convertPoint(WorldCamera.position, fromNode: World)
World.runAction(SKAction.moveTo(CGPoint(x:World.position.x , y:World.position.y - cameraPositionInScene.y), duration: 1.0))
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
if(Platform1.position.y < (Player.position.y - self.frame.size.height / 2)){
Platform1.position = CGPointMake(self.frame.size.width / 2, Platform7.position.y + self.frame.size.height / 4.5)
Platform1.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform1.position.y + 30))
}
if(Platform2.position.y < (Player.position.y - self.frame.size.height / 2)){
Platform2.position = CGPointMake(self.frame.size.width / 2, Platform1.position.y + self.frame.size.height / 4.5)
Platform2.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform2.position.y + 30))
}
if(Platform3.position.y < (Player.position.y - self.frame.size.height / 2)){
Platform3.position = CGPointMake(self.frame.size.width / 2, Platform2.position.y + self.frame.size.height / 4.5)
Platform3.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform3.position.y + 30))
}
if(Platform4.position.y < (Player.position.y - self.frame.size.height / 2)){
Platform4.position = CGPointMake(self.frame.size.width / 2, Platform3.position.y + self.frame.size.height / 4.5)
Platform4.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform4.position.y + 30))
}
if(Platform5.position.y < (Player.position.y - self.frame.size.height / 2)){
Platform5.position = CGPointMake(self.frame.size.width / 2, Platform4.position.y + self.frame.size.height / 4.5)
Platform5.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform5.position.y + 30))
}
if(Platform6.position.y < (Player.position.y - self.frame.size.height / 2)){
Platform6.position = CGPointMake(self.frame.size.width / 2, Platform5.position.y + self.frame.size.height / 4.5)
Platform6.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform6.position.y + 30))
}
if(Platform7.position.y < (Player.position.y - self.frame.size.height / 2)){
Platform7.position = CGPointMake(self.frame.size.width / 2, Platform6.position.y + self.frame.size.height / 4.5)
Platform7.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: Platform7.position.y + 30))
}
}

Answer 1

Your problem is you do not create any kind of check that moving the platform has already spawned an enemy. Sure, you move the platform, but until your player moves, it will constantly spawn enemies. I do not see where this is happening, but you should spawn enemy when you move the platform, not on your update
Edit:
yikes, I see it now, this is some ugly code lol, In all those ifs that move the platform, you should spawn the enemy. But this needs to be worked to also check if the previous platform is below the current, not above
Edit++:
Upon further review and added details, try something like this instead:
First, give all Platforms a name "Platform"
Then
override func update(currentTime: CFTimeInterval) {
for node in scene.children
{
if (node.name == "Platform" && !node.intersectsNode(scene) && node.position.y < player.y - (self.frame.size.height / 4.5))
{
let platform = node as! SKSpriteNode
platform.position.y += (7 * (self.frame.size.height / 4.5))
platform.color = SKColor.redColor()
SpawnEnemy(CGPoint(x: self.frame.size.width / 2, y: platform.position.y + 30))
}
}
}
Question: How does this even work, I would just check if a platform hits a certain point in the scene, recycle it, instead of having to check every single platform and moving it's previous one

Answer 2

so you're spawning an enemy on every frame.. thats going to be way too many enemies.. I'm still not totally following the exact architecture of your game, but this might help you out.
get delta time to see how much time has passed.. and every 10 seconds (or whatever) call your spawn enemy code instead of calling it on every frame
// time values
var delta = NSTimeInterval(0)
var last_update_time = NSTimeInterval(0)
let spawnTimerMax = NSTimeInterval(10)
var spawnTimer = NSTimeInterval(0)
override func update(currentTime: NSTimeInterval) {
if last_update_time == 0.0 {
delta = 0
} else {
delta = currentTime - last_update_time
}
last_update_time = currentTime
// ten seconds elapsed, spawn enemy and restart.
spawnTimer += delta
if spawnTimer >= spawnTimerMax {
// your spawn code goes here
spawnTimer = 0
}
}