Customize an IOS Application's Navigation Bar Back Button in SwiftUI

AppDelegate.swift

import Foundation
import SwiftUI

class AppDelegate: NSObject, UIApplicationDelegate {
    func application(_ application: UIApplication,
                     didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey : Any]? = nil
    ) -> Bool {
        customizeNavigationBarAppearance()
    }
    
    func customizeNavigationBarAppearance() {
        let customAppearance = UINavigationBarAppearance()
        customAppearance.configureWithOpaqueBackground()
        
        let textAttrs: [NSAttributedString.Key : Any] = [
            .foregroundColor: UIColor(.white),
            .font: UIFont(name: "ProximaNova-Medium", size: 16)!
        ]
        customAppearance.titleTextAttributes = textAttrs
        customAppearance.largeTitleTextAttributes = textAttrs
        customAppearance.backgroundColor = UIColor(.systemBlue)
        customAppearance.shadowColor = .clear

        let config = UIImage.SymbolConfiguration(font: UIFont(name: "ProximaNova-Light", size: 14)!)
        let backIndicatorImage = UIImage(systemName: "chevron.left", withConfiguration: config)

        customAppearance.setBackIndicatorImage(backIndicatorImage, transitionMaskImage: backIndicatorImage)
        customAppearance.backButtonAppearance.normal.titleTextAttributes = textAttrs
        
        // global nav bar image tint, can't override it on button by button basis without wholly custom button
        UIBarButtonItem.appearance().tintColor = .white
        
        let proxy = UINavigationBar.appearance()
        proxy.prefersLargeTitles = false
        proxy.scrollEdgeAppearance = customAppearance
        proxy.compactAppearance = customAppearance
        proxy.standardAppearance = customAppearance
        proxy.compactScrollEdgeAppearance = customAppearance
    }
}