 extension UIColor
 {
     fileprivate struct AssociatedKeys
-    {
-        static var defNavBarBarTintColor: UIColor = UIColor.white // UIColor.init(red: 0/255.0, green: 175/255.0, blue: 240/255.0, alpha: 1)
-        static var defNavBarTintColor: UIColor = UIColor.white
+    {   // default is system attributes
+        static var defNavBarBarTintColor: UIColor = UIColor.white
+        static var defNavBarTintColor: UIColor = UIColor(red: 0, green: 0.478431, blue: 1, alpha: 1.0)
         static var defStatusBarStyle: UIStatusBarStyle = UIStatusBarStyle.default
     }
     class var defaultNavBarBarTintColor: UIColor {

        }
    }
    
    class var defaultEffectAlpha: CGFloat {
        get {
            return 1.0
        }

        toColor.getRed(&toRed, green: &toGreen, blue: &toBlue, alpha: &toAlpha)
        
        // calculate middle color RGBA
        let newRed = fromRed + (toRed - fromRed) * percent
        let newGreen = fromGreen + (toGreen - fromGreen) * percent
        let newBlue = fromBlue + (toBlue - fromBlue) * percent
        let newAlpha = fromAlpha + (toAlpha - fromAlpha) * percent
        return UIColor(red: newRed, green: newGreen, blue: newBlue, alpha: newAlpha)
    }
    
    // Calculate the middle alpha
