Set UINavigationBar's gradient color using IBInspectable - ios

Question

So this is my custom class for UINavigationBar :
import UIKit
#IBDesignable
class GradientNavigationBar: UINavigationBar {
#IBInspectable var firstColor: UIColor = UIColor.clear {
didSet {
updateView()
}
}
#IBInspectable var secondColor: UIColor = UIColor.clear {
didSet {
updateView()
}
}
#IBInspectable var isHorizontal: Bool = true {
didSet {
updateView()
}
}
override class var layerClass: AnyClass {
get {
return CAGradientLayer.self
}
}
func updateView() {
let layer = self.layer as! CAGradientLayer
layer.colors = [firstColor, secondColor].map {$0.cgColor}
if (isHorizontal) {
layer.startPoint = CGPoint(x: 0, y: 0.5)
layer.endPoint = CGPoint (x: 1, y: 0.5)
} else {
layer.startPoint = CGPoint(x: 0.5, y: 0)
layer.endPoint = CGPoint (x: 0.5, y: 1)
}
setBackgroundImage(layer.createGradientImage(), for: UIBarMetrics.default)
}
}
CAGradientLayer extension :
import Foundation
import UIKit
extension CAGradientLayer {
convenience init(frame: CGRect, colors: [UIColor]) {
self.init()
self.frame = frame
self.colors = []
for color in colors {
self.colors?.append(color.cgColor)
}
startPoint = CGPoint(x: 0, y: 0)
endPoint = CGPoint(x: 0, y: 1)
}
func createGradientImage() -> UIImage? {
var image: UIImage? = nil
UIGraphicsBeginImageContext(bounds.size)
if let context = UIGraphicsGetCurrentContext() {
render(in: context)
image = UIGraphicsGetImageFromCurrentImageContext()
}
UIGraphicsEndImageContext()
return image
}
}
Storyboard attributes :
Output on Storyboard :
Expected output :
Note : I can easily do this using just code. What I want is using IBInspectable so that I can directly set this via IB.