Swift Ints and some Doubles working but not all Doubles - ios

Question

What I am trying to do is increase the rate that the method spawnEnemy() is called on, and it works well using the starred numbers as Ints, but I felt like it goes by way too quickly so I thought of using Doubles and using the decimal point. However, if I go into the tenths spot of subtracting an amount from spawnRate in
self.spawnRate=spawnRate - 1.0 (I use anything but 0) spawnEnemy() will only be called on once in the simulator then nothing happens. Any advice or suggestions would be great. Thank you!
import UIKit
class ViewController: UIViewController {
#IBOutlet weak var scoreLabel: UILabel!
var points: Int = 0
var tickCount=0.0 // **
var spawnRate=15.0 // Spawn every 15 seconds to start with..... **
var spawnTimer:NSTimer!
override func viewDidLoad() {
super.viewDidLoad()
self.tickCount=self.spawnRate
self.spawnTimer=NSTimer.scheduledTimerWithTimeInterval(0.1, target: self, selector: Selector("tick"), userInfo: nil, repeats: true)
}
func tick() {
if (--tickCount == 0) { // **
self.spawnEnemy()
self.spawnRate=spawnRate - 0.5 // Change this to determine how quickly the spawn rate increases..... **
self.tickCount=self.spawnRate
}
}
func randomPoint() -> CGPoint {
let randomPoint: CGPoint = CGPoint(x:CGFloat(arc4random()%320),y:CGFloat(568-arc4random()%390))
return randomPoint
}
func randomColor() -> UIColor {
let red = CGFloat(drand48())
let green = CGFloat(drand48())
let blue = CGFloat(drand48())
return UIColor(red: red, green: green, blue: blue, alpha: 1.0)
}
func spawnEnemy() {
let enemy: UIButton = UIButton(frame: CGRect(x: 160, y: 160, width: 100, height: 100))
enemy.backgroundColor = randomColor()
enemy.center = randomPoint()
enemy.addTarget(self, action: Selector("buttonPushed:"), forControlEvents: UIControlEvents.TouchUpInside)
self.view.addSubview(enemy)
}
func buttonPushed(sender : UIButton) {
if sender.frame.height < 50 || sender.frame.width < 50 {
sender.frame = CGRectMake(sender.frame.origin.x, sender.frame.origin.y, 50, 50)
sender.backgroundColor = randomColor()
sender.center = randomPoint()
return
}
while sender.backgroundColor != UIColor.blackColor() {
points = points + 1
scoreLabel.textAlignment = .Center
scoreLabel.text = "\(points)"
scoreLabel.backgroundColor = UIColor.blackColor()
sender.backgroundColor = UIColor.blackColor()
}
}
}

Answer 1

I think what's happening is you're trying to test a double with the equality operator. The problem is that there's always a bit of complexity in how doubles are stored that makes it very difficult to compare them with equality. Instead you need to do something like this:
if (--tickCount <= 0) {
That way you catch it going negative for sure, otherwise it can go right past 0 and continue to count down.