         }
     }
     
-    internal var thumbTintColor: UIColor = UIColor.whiteColor() {
+    internal var thumbTintColor: UIColor = .white {
         willSet {
             backgroundView.backgroundColor = isOn ? onThumbTintColor : newValue
         }
     }
-    internal var onThumbTintColor: UIColor = UIColor.whiteColor() {
+    internal var onThumbTintColor: UIColor = .white {
         willSet {
             backgroundView.backgroundColor = isOn ? newValue : thumbTintColor
         }
     }
-    internal var shadowColor: UIColor = UIColor.grayColor() {
+    internal var shadowColor: UIColor = .gray {
         willSet {
-            backgroundView.layer.shadowColor = newValue.CGColor
+            backgroundView.layer.shadowColor = newValue.cgColor
         }
     }
     

private let thumbSignWidth = CGFloat(7)

internal class PMZISwitchAnimatedThumb: UIView {

    // MARK: - Properties -
    // MARK: internal
    internal var animationProgress: CGFloat = 0 {

    private var thumbAnimationGroup: CAAnimationGroup!
    private var isOn: Bool = false
    private var isTracking: Bool = false
    
    // MARK: - Lifecycle -
    /**
     *   Initialization
     */
    
    required internal init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
