сохранение индекса в состоянии по клику, странное поведение

Вот что я делаю в Swift 3

override func viewDidLoad() {
    super.viewDidLoad()
    timerLabel.textColor = UIColor(patternImage: gradientImage(size: timerLabel.frame.size, color1: CIColor(color: UIColor.green), color2: CIColor(color: UIColor.red), direction: .Left))
}

func gradientImage(size: CGSize, color1: CIColor, color2: CIColor, direction: GradientDirection = .Up) -> UIImage {

    let context = CIContext(options: nil)
    let filter = CIFilter(name: "CILinearGradient")
    var startVector: CIVector
    var endVector: CIVector

    filter!.setDefaults()

    switch direction {
    case .Up:
        startVector = CIVector(x: size.width * 0.5, y: 0)
        endVector = CIVector(x: size.width * 0.5, y: size.height)
    case .Left:
        startVector = CIVector(x: size.width, y: size.height * 0.5)
        endVector = CIVector(x: 0, y: size.height * 0.5)
    case .UpLeft:
        startVector = CIVector(x: size.width, y: 0)
        endVector = CIVector(x: 0, y: size.height)
    case .UpRight:
        startVector = CIVector(x: 0, y: 0)
        endVector = CIVector(x: size.width, y: size.height)
    }

    filter!.setValue(startVector, forKey: "inputPoint0")
    filter!.setValue(endVector, forKey: "inputPoint1")
    filter!.setValue(color1, forKey: "inputColor0")
    filter!.setValue(color2, forKey: "inputColor1")

    let image = UIImage(cgImage: context.createCGImage(filter!.outputImage!, from: CGRect(x: 0, y: 0, width: size.width, height: size.height))!)
    return image
}