Why is my if statement code not running in swift?

import UIKit
class ViewController: UIViewController {
    var timerCount = 5
    var timerRunning = false
    var timer = NSTimer()

    func shuffle<C: MutableCollectionType where C.Index == Int>(var list: C) -> C {
        let c = count(list)
        for i in 0..<(c - 1) {
            let j = Int(arc4random_uniform(UInt32(c - i))) + i
            swap(&list[i], &list[j])
        }
        return list
    }

    func counting(){
        timerCount -= 1
        timerLabel.text = "\(timerCount)"
    }

    @IBOutlet weak var alphebetLabel: UILabel!
    @IBOutlet weak var timerLabel: UILabel!
    @IBOutlet weak var sign1: UIImageView!
    @IBOutlet weak var sign2: UIImageView!
    @IBOutlet weak var sign3: UIImageView!
    @IBOutlet weak var sign4: UIImageView!
    @IBOutlet weak var sign5: UIImageView!
    @IBOutlet weak var color1: UIImageView!
    @IBOutlet weak var color2: UIImageView!
    @IBOutlet weak var color3: UIImageView!
    @IBOutlet weak var color4: UIImageView!
    @IBOutlet weak var color5: UIImageView!
    @IBOutlet weak var blueButton: UIButton!
    @IBOutlet weak var purpleButton: UIButton!
    @IBOutlet weak var orangeButton: UIButton!
    @IBOutlet weak var yellowButton: UIButton!
    @IBOutlet weak var redButton: UIButton!

    override func viewDidLoad() {
        var gameViewStillRunning = true
        var sign1RandNum = arc4random_uniform(3) + 1
        var sign2RandNum = arc4random_uniform(4) + 1
        var sign3RandNum = arc4random_uniform(4) + 1
        var sign4RandNum = arc4random_uniform(4) + 1
        var sign5RandNum = arc4random_uniform(4) + 1
        var colorArray = ["orangeBrick", "blueBrick", "yellowBrick",     "redBrick", "purpleBrick"]
        var shuffledColorArray: Array = shuffle(colorArray)
        self.color1.image = UIImage(named: shuffledColorArray[0])
        self.color2.image = UIImage(named: shuffledColorArray[1])
        self.color3.image = UIImage(named: shuffledColorArray[2])
        self.color4.image = UIImage(named: shuffledColorArray[3])
        self.color5.image = UIImage(named: shuffledColorArray[4])

        var correctAnswer = 0

        switch sign1RandNum{
            case 1:
            self.sign1.image = UIImage(named: "blank")

            case 2:
            self.sign1.image = UIImage(named: "forward")
            case 3:
            self.sign1.image = UIImage(named: "fastForward")
            case 4:
            self.sign1.image = UIImage(named: "backSpace")
            default:
            break
        }
        switch sign2RandNum{
            case 1:
            self.sign2.image = UIImage(named: "blank")
            case 2:
            self.sign2.image = UIImage(named: "forward")
            case 3:
            self.sign2.image = UIImage(named: "fastForward")
            case 4:
            self.sign2.image = UIImage(named: "backSpace")
            default:
            break
        }
        switch sign3RandNum{
            case 1:
            self.sign3.image = UIImage(named: "blank")
            case 2:
            self.sign3.image = UIImage(named: "forward")
            case 3:
            self.sign3.image = UIImage(named: "fastForward")
            case 4:
            self.sign3.image = UIImage(named: "backSpace")
            default:
            break
        }
        switch sign4RandNum{
            case 1:
            self.sign4.image = UIImage(named: "blank")
            case 2:
            self.sign4.image = UIImage(named: "forward")
            case 3:
            self.sign4.image = UIImage(named: "fastForward")
            case 4:
            self.sign4.image = UIImage(named: "backSpace")
            default:
            break
        }
        switch sign5RandNum{
            case 1:
            self.sign5.image = UIImage(named: "blank")
            case 2:
            self.sign5.image = UIImage(named: "forward")
            case 3:
            self.sign5.image = UIImage(named: "fastForward")
            case 4:
            self.sign5.image = UIImage(named: "backSpace")
            default:
            break
        }

        if timerRunning == false{
            timer = NSTimer.scheduledTimerWithTimeInterval(1, target: self, selector: Selector("counting"), userInfo: nil, repeats: true)
            timerRunning = true
        }

        if timerLabel.text == "0"{
            self.alphebetLabel.text = "B"
        }
    }
}

Although all of this code runs fine and the project builds, the if statement at the end that changes the text of tester label is not being run. The title does not change at all once the countdown hits 0. I have also tried implanting other functions into that if statement but the code is never reached. Any suggestions?