Changing the interval of a timer in an if statement - swift

Question

I'm creating a game that involves a timer that spawns objects every second that fall down the screen. To gain points you must catch the objects.
I want the rate of spawning to increase once the player reaches a certain amount of points.
I have tried to do this by assigning the interval of the timer an integer (SpeedNumber) value of 1 second to start with and have created and if statement that is supposed to change that integer to 0.5 once the player reaches a certain amount of points. This makes sense to me but it is not working.
Why is this not working and what should I change?
import SpriteKit
struct physicsCatagory {
static let person : UInt32 = 0x1 << 1
static let Ice : UInt32 = 0x1 << 2
static let IceTwo : UInt32 = 0x1 << 3
static let IceThree : UInt32 = 0x1 << 4
static let Score : UInt32 = 0x1 << 5
}
class GameScene: SKScene, SKPhysicsContactDelegate {
var scorenumber = Int()
var lifenumber = Int()
var SpeedNumber : Double = 0.5
var person = SKSpriteNode(imageNamed: "Person")
let Score = SKSpriteNode()
var ScoreLable = SKLabelNode()
override func didMoveToView(view: SKView) {
self.scene?.backgroundColor = UIColor.purpleColor()
physicsWorld.contactDelegate = self
self.scene?.size = CGSize(width: 640, height: 1136)
lifenumber = 0
SpeedNumber = 1
Score.size = CGSize(width: 648, height: 1)
Score.position = CGPoint(x: 320, y: -90)
Score.physicsBody = SKPhysicsBody(rectangleOfSize: Score.size)
Score.physicsBody?.affectedByGravity = false
Score.physicsBody?.dynamic = false
Score.physicsBody?.categoryBitMask = physicsCatagory.Score
Score.physicsBody?.collisionBitMask = 0
Score.physicsBody?.contactTestBitMask = physicsCatagory.IceThree
Score.color = SKColor.blueColor()
self.addChild(Score)
person.position = CGPointMake(self.size.width/2, self.size.height/12)
person.setScale(0.4)
person.physicsBody = SKPhysicsBody(rectangleOfSize: person.size)
person.physicsBody?.affectedByGravity = false
person.physicsBody?.categoryBitMask = physicsCatagory.person
person.physicsBody?.contactTestBitMask = physicsCatagory.Ice
person.physicsBody?.collisionBitMask = physicsCatagory.Ice
person.physicsBody?.dynamic = false
ScoreLable.position = CGPoint(x: self.frame.width / 2, y: 1000)
ScoreLable.text = "\(scorenumber)"
ScoreLable.fontColor = UIColor.yellowColor()
ScoreLable.fontSize = 100
ScoreLable.fontName = "Zapfino "
self.addChild(ScoreLable)
var IceThreeTimer = NSTimer.scheduledTimerWithTimeInterval(SpeedNumber, target: self, selector: ("spawnThirdIce"), userInfo: nil, repeats: true)
self.addChild(person)
}
func didBeginContact(contact: SKPhysicsContact) {
let firstBody = contact.bodyA
let secondBody = contact.bodyB
if firstBody.categoryBitMask == physicsCatagory.person && secondBody.categoryBitMask == physicsCatagory.IceThree || firstBody.categoryBitMask == physicsCatagory.IceThree && secondBody.categoryBitMask == physicsCatagory.person{
scorenumber++
if scorenumber == 5 {
SpeedNumber = 0.5
}
ScoreLable.text = "\(scorenumber)"
CollisionWithPerson(firstBody.node as! SKSpriteNode, Person: secondBody.node as! SKSpriteNode)
}
if firstBody.categoryBitMask == physicsCatagory.Score && secondBody.categoryBitMask == physicsCatagory.IceThree ||
firstBody.categoryBitMask == physicsCatagory.IceThree && secondBody.categoryBitMask == physicsCatagory.Score{
lifenumber++
if lifenumber == 3{
self.view?.presentScene(EndScene())
}
//self.view?.presentScene(EndScene())
}
}
func CollisionWithPerson (Ice: SKSpriteNode, Person: SKSpriteNode){
Person.removeFromParent()
}
func spawnThirdIce(){
var Ice = SKSpriteNode(imageNamed: "Ice")
Ice.setScale(0.9)
Ice.physicsBody = SKPhysicsBody(rectangleOfSize: Ice.size)
Ice.physicsBody?.categoryBitMask = physicsCatagory.IceThree
Ice.physicsBody?.contactTestBitMask = physicsCatagory.person | physicsCatagory.Score
Ice.physicsBody?.affectedByGravity = false
Ice.physicsBody?.dynamic = true
let MinValue = self.size.width / 8
let MaxValue = self.size.width - 20
let SpawnPoint = UInt32(MaxValue - MinValue)
Ice.position = CGPoint(x: CGFloat(arc4random_uniform(SpawnPoint)), y: self.size.height)
self.addChild(Ice)
let action = SKAction.moveToY(-85, duration: 2.5)
let actionDone = SKAction.removeFromParent()
Ice.runAction(SKAction.sequence([action,actionDone]))
}
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let location = touch.locationInNode(self)
person.position.x = location.x
}
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in touches {
let location = touch.locationInNode(self)
person.position.x = location.x
}
}
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
}
}

Answer 1

You could do what you want as follows:
First declare 2 properties (in your class but outside all the function definitions)
var timeOfLastSpawn: CFTimeInterval = 0.0
var timePerSpawn: CFTimeInterval = 1.0
Then, in Update, check to see if the timePerSpawn has been exceeded. If so, call your spawn process which spawns new objects and then reset the time since the last spawn:
override func update(currentTime: CFTimeInterval) {
/* Called before each frame is rendered */
if (currentTime - timeOfLastSpawn > timePerSpawn) {
spawnObject()
self.timeOfLastSpawn = currentTime
}
}
func spawnObject() {
// Your spawn code here
}
The advantage of making the spawn process a separate function is that you can call it from didMoveToView or any other place to spawn objects outside of the normal time-controlled cycle.
You can change the value of timePerSpawn as necessary to control the rate at which objects are spawned.
You could also look into creating an SKAction that runs spawnObject at specified time intervals, but I think to change the rate at which objects are spawned, you'll have to delete and re-create the SKAction, but your could do this in a setter for timePerSpawn.
You shouldn't really use NSTimer is SpriteKit, as the SpriteKit engine will be unaware of what the timer is doing and can't control it (one example is that the timer keeps running if the set the scene to paused).

Answer 2

You should move your declaration of var IceThreeTimer to the class level (outside of the method, right where you declare SpeedNumber. This will make sure that your handle to the pointer will be available in both the didMoveToView and didBeginContact methods.
In didMoveToView you change your declaration to:
// I removed the "var"
IceThreeTimer = NSTimer.scheduledTimerWithTimeInterval(SpeedNumber, target: self, selector: ("spawnThirdIce"), userInfo: nil, repeats: true)
Then in didBeginContact you modify:
if scorenumber == 5 {
SpeedNumber = 0.5
// Stop the already running timer
IceThreeTimer.invalidate()
// Schedule a new timer
IceThreeTimer = NSTimer.scheduledTimerWithTimeInterval(SpeedNumber, target: self, selector: ("spawnThirdIce"), userInfo: nil, repeats: true)
}