Hey guys I've been working through the SpriteKit project for this project but the second challenge is quite tough. I understand that you would have to call gameTimer.invalidate() to prevent multiple timers from running, but I guess its really hard to tell if the timer is working or not as the game is so fast. I'm also a little confused about where to exactly write the timer...long story short, what would be the best way for the timer to reduce for every 20 enemies?

newTimer = Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { timer in
for enemies in self.possibleEnemies {
self.runTimer -= 0.1
print(self.newTimer as Any)
if enemies.count == 20 {

self.newTimer?.invalidate()

}
} //didn't seem to do anything.

Apologies if my code is messy. I tried to put this in createEnemy function as I thought it would run from there but, where would be the correct place to put the code? Would I need to create a new func and call it from inside the createEnemy func or somewhere else?

Thanks for your time guys.