How can you track calls to the viewDidLoad method in all instances of controllers in an application?

To track calls to the viewDidLoad method in all instances of controllers in iOS, you can use method swizzling — a runtime technique for dynamically replacing method implementations.

Example in Swift:

import UIKit

extension UIViewController {
    static let swizzleViewDidLoad: Void = {
        let originalSelector = #selector(viewDidLoad)
        let swizzledSelector = #selector(swizzled_viewDidLoad)

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

        method_exchangeImplementations(originalMethod, swizzledMethod)
    }()

    @objc func swizzled_viewDidLoad() {
        // Call the original viewDidLoad (now swizzled_viewDidLoad)
        swizzled_viewDidLoad()

        // Logging or other logic
        print("viewDidLoad called for \(type(of: self))")
    }
}

// Call swizzling once, for example, in AppDelegate
UIViewController.swizzleViewDidLoad

This approach allows intercepting calls to viewDidLoad for all controllers without modifying their original code.