iOS Gradient Navigation Bar Swift 4

Decorating iOS 12 and below UINavigationController Gradient Color by Creating an extension for UINavigationBar. Create a gradient layer and add it as the background of the navigation bar. 

UIImage extension allows creating an image from CALayer.

	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
	}

view raw getImageFrom CALayer.swift hosted with ❤ by GitHub

This function creates and returns a gradient image. Changing the startPoint and endPoint (currently horizontal) to change the gradient direction to apply on Navigation Controller.

Then add the following function for complete UINavigationBar Extensions. 

	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
	}
	}

view raw UINavigationBarExtension.swift hosted with ❤ by GitHub

Usage on NavigationController:

	override func viewWillAppear(_ animated: Bool) {
	navigationController?.navigationBar.setGradientBackground(to: self.navigationController!)
	}

view raw GradientNavigationController.swift hosted with ❤ by GitHub

If you have any questions please post your comments below.
Thank you!