Customize Navigation Bar Font and Color

NavigationBar+CustomFont.swift

//  NavigationBar+Custom.swift

import UIKit

class ViewController: UIViewController {
  
  override func viewDidLoad() {
        super.viewDidLoad()
        
        // navigation bar title
        self.navigationItem.title = "Navigation Bar"
        // configure navigation bar
        navigationController?.configure(withFontSize: 24.0, andWeight: .black)
    }

}

extension UINavigationController {
    
    /// Customize Navigation Bar Font and Color
    func configure(withFontSize size: CGFloat, andWeight weight: UIFont.Weight = .regular) {
        // status bar color: black means the background is black and text is white
        self.navigationBar.barStyle = .black
        // background color
        self.navigationBar.barTintColor = .black
        // color left and right navigation bar items
        self.navigationBar.tintColor = .white
        // font size and weight
        var customFont = UIFont()
        //
        if let descriptor = UIFont.systemFont(ofSize: size, weight: weight).fontDescriptor.withDesign(.rounded) {
            // set rounded system font
            customFont = UIFont(descriptor: descriptor, size: size)
        } else {
            // set default font design if rounded not available
            customFont = UIFont.systemFont(ofSize: size, weight: weight)
        }
        // title attributes
        self.navigationBar.titleTextAttributes = [
            // title custom font size and weight
            NSAttributedString.Key.font: customFont,
            // title color
            NSAttributedString.Key.foregroundColor: UIColor.white
        ]
    }
}