Track screen Name Firebase from iOS app using single file and single line. Using Objective C feature: Method Swizzling

Only add logger function in app delegate once and get logs from every screen:

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

        // Override point for customization after application launch.

        // Ensure swizzling happens at app launch to log screens

        UIViewController.swizzleViewDidAppear
//// rest of your code...........

Create a logger File "ViewContronller+Extension.swift"

import UIKit 
import Foundation

import FirebaseAnalytics

extension UIViewController {

    /// Tracks the screen view event using Firebase Analytics.

    /// - Parameters:

    ///   - screenName: Custom name for the screen. If not provided, the view controller's class name is used.

    ///   - screenClass: Optional custom class name. Defaults to the view controller's class.

    func trackScreenView(screenName: String? = nil, screenClass: String? = nil) {

        let name = screenName ?? String(describing: type(of: self))

        let className = screenClass ?? String(describing: type(of: self))

        Analytics.logEvent(AnalyticsEventScreenView, parameters: [

            AnalyticsParameterScreenName: name,

            AnalyticsParameterScreenClass: className

        ])

    }

    /// Returns the name of the current screen, which is the view controller's class name.

     var currentScreenName: String {

         return String(describing: type(of: self))

     }

     /// Returns the class name of the current screen.

     var currentScreenClass: String {

         return NSStringFromClass(type(of: self))

     }

    /// Logs the screen view event using Firebase Analytics.

      func logScreenViewEvent() {

          print("FireBase Log: CSreenName \(currentScreenName), CScreenClass: \(currentScreenClass)")

          Analytics.logEvent(AnalyticsEventScreenView, parameters: [

              AnalyticsParameterScreenName: currentScreenName,

              AnalyticsParameterScreenClass: currentScreenClass

          ])

      }

}

extension UIViewController {

    // Swizzle the `viewDidAppear` method

    static let swizzleViewDidAppear: Void = {

        let originalSelector = #selector(UIViewController.viewDidAppear(_:))// original fuinction

        let swizzledSelector = #selector(swizzled_viewDidAppear(_:))// Swizzled Function

        guard let originalMethod = class_getInstanceMethod(UIViewController.self, originalSelector),

              let swizzledMethod = class_getInstanceMethod(UIViewController.self, swizzledSelector) else { return}

        method_exchangeImplementations(originalMethod, swizzledMethod)// Swicth the functions

    }()

    

    // New implementation of `viewDidAppear`

    @objc func swizzled_viewDidAppear(_ animated: Bool) {

        swizzled_viewDidAppear(animated)// Call the original `viewDidAppear` (actually the swizzled method)

        logScreenViewEvent()// Log the screen view event

    }

}

// Ensure swizzling happens at app launch

extension UIApplication {

    private static let runOnce: Void = {

        UIViewController.swizzleViewDidAppear

    }()

    

    override open var next: UIResponder? { // calling original functionality after logging

        UIApplication.runOnce

        return super.next

    }

}