UINavigationBarExtension.swift

import Foundation
import UIKit

extension UINavigationBar {
    
    func setGradientBackground(to navController: UINavigationController) {
        
        let gradient = CAGradientLayer()
        var bounds = navController.navigationBar.bounds
        bounds.size.height += UIApplication.shared.statusBarFrame.size.height
        gradient.frame = bounds
        gradient.colors = [ColorName.secoandary.color.cgColor, ColorName.primary.color.cgColor]
        gradient.startPoint = CGPoint(x: 0, y: 0)
        gradient.endPoint = CGPoint(x: 0, y: 1)
        
        if let image = getImageFrom(gradientLayer: gradient) {
            navController.navigationBar.setBackgroundImage(image, for: UIBarMetrics.default)
        }
    }
    
    func getImageFrom(gradientLayer:CAGradientLayer) -> UIImage? {
        var gradientImage:UIImage?
        UIGraphicsBeginImageContext(gradientLayer.frame.size)
        if let context = UIGraphicsGetCurrentContext() {
            gradientLayer.render(in: context)
            gradientImage = UIGraphicsGetImageFromCurrentImageContext()?.resizableImage(withCapInsets: UIEdgeInsets.zero, resizingMode: .stretch)
        }
        UIGraphicsEndImageContext()
        return gradientImage
    }
    
}