NSTimer.scheduledTimerWithTimeInterval() with variable delay

Question

I have a function that need to be called every x second. At the begining x = 5 but everytime it calls this function x need to decrement by a certain number. I know how to do it if x is constant:

override func didMoveToView(view: SKView) {
    NSTimer.scheduledTimerWithTimeInterval(5, target: self, selector: Selector("function"), userInfo: nil, repeats: true)
}

func function(){
    println("TEST")
}

How could I decrement the delay between each function calls each time it gets called?

Answer 1

I would change your code like this:

var timeDuration: NSTimeInterval = 5

override func didMoveToView(view: SKView) {
   NSTimer.scheduledTimerWithTimeInterval(timeDuration, target: self, selector: Selector("function"), userInfo: nil, repeats: false)
}

func function(){
    println("TEST")
    timeDuration -= 1
    if timeDuration > 0{
        NSTimer.scheduledTimerWithTimeInterval(timeDuration, target: self, selector: Selector("function"), userInfo: nil, repeats: false)
    }
}

This should work, have not tested it.