Selector is not fired from scheduledTimerWithTimeInterval

Question

I checked the existing posts on this topic and also googled it, but I am not able to identify my mistake or make this work for me. I have a function iterativeDeepening() inside the class ChessPlayer. After say 15 seconds I want to stop further iterations within the function. In the code below, the function "flagSetter" is never invoked. If I use NSTimer.fire() the function is invoked immediately and not after 15 seconds. I tried placing the flagSetter function before or after iterativeDeepening(). Either case does not work. What have I done incorrectly?

class ChessPlayer {
    var timeoutFlag = false
    //Code

    func iterativeDeepening() {

        ***//variables and constants***

        let timer = NSTimer.scheduledTimerWithTimeInterval(15.0, target: self, selector: #selector(self.flagSetter), userInfo: nil, repeats: false)

        ***while minDepth <= maxDepth
        {
            // Loop iteration code
            if timeoutFlag { break out of loop }
        }***

    }

    @objc func flagSetter(timer: NSTimer) {
        print("flag changed to true")
        self.timeoutFlag = true
        timer.invalidate()
    }
}

---

The requirement:

1. computerThinking() is fired from GameScene from human move's action completion handler.
2. GameScene.computerThinking() invokes ChessPlayer.iterativeDeepening()
3. iterativeDeepening runs a while loop incrementing "depth". For each "depth" an optimal move at that depth is evaluated. Higher the depth, more detailed the evaluation.
4. after 15.0 seconds i want to break out of the while loop with the depth and optimal move available at that point of time.

Answer 1

Here is your solution: define timer outside of the function so you can invalidate it from another function. Right now, your timer is defined inside a function so it can only be altered inside that function, but that is not what you want. Fix it by doing the following: right below var timeoutFlag = false put var timer = NSTimer(). Then inside your function iterativeDeepening() get rid of the let. Then it will all work!!

---

Here's what your code should be, adapted from Hasya's answer and your provided code.

class ChessPlayer {
// Declare timer and timeoutFlag
var timer = NSTimer()   
var timeoutFlag = false

func iterativeDeepening() {

self.timer = NSTimer.scheduledTimerWithTimeInterval(15.0, target: self, selector: “timerEventOccured”, userInfo: nil, repeats: true)
}

func timerEventOccured() {
        print("timerEventOccured was called.")
        timeoutFlag = true
        self.timer.invalidate()
    }

}

override func viewDidUnload() {
super.viewDidUnload()
self.timer.invalidate()
}
}

Answer 2

I am a lover of Objective-c and never used Swift yet in my projects. Googling NSTimer Swift, I found out the following steps to implement NSTimer correctly.

we need to define our NSTimer. The first variable that we are going to need is a variable called timer of type NSTimer. We do this like:

var timer = NSTimer()

Start NSTimer timer:

timer = NSTimer.scheduledTimerWithTimeInterval(15.0, target:self, selector:#selector(ChessPlayer.flagSetter(_:)), userInfo: nil, repeats: false)

And your method flagSetter should be defined as this:

func flagSetter(timer: NSTimer) {
        print("flag changed to true")
        self.timeoutFlag = true
        timer.invalidate()
}

This will now surely work as I've made my very first app, just for this question, made in Swift. Check how I put my selector. You're right with the warnings by the way.

If you need more information about Selectors, check this thread: @selector() in Swift?