Swift-Obj-c Method swizzling for common task.

UIViewController+Swizzling.swift

extension UIViewController {
    
    @objc func analytics() {
        print("Analytics related implementation")
        analytics()
    }
    
    
    static func swizzle() {
        // We will swizzle here
        let originalImpl =  class_getInstanceMethod(UIViewController.self, #selector(UIViewController.viewDidLoad))
        let swizzleImpl = class_getInstanceMethod(UIViewController.self, #selector(UIViewController.analytics))
        method_exchangeImplementations(swizzleImpl!, originalImpl!)
        print("swizzled")
    }
}

class MyViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

UIViewController.swizzle()

let obj = MyViewController()
obj.viewDidLoad()


/* TEST Section
class InternalUIViewController : UIViewController {
    override func viewDidLoad() {
        print("InternalUIViewController viewDidLoad implementation")
    }
}

extension InternalUIViewController {
    
    @objc func analytics() {
        print("Analytics related implementation")
        analytics()
    }
    
    
    static func swizzle() {
        // We will swizzle here
        let originalImpl =  class_getInstanceMethod(InternalUIViewController.self, #selector(InternalUIViewController.viewDidLoad))
        let swizzleImpl = class_getInstanceMethod(InternalUIViewController.self, #selector(InternalUIViewController.analytics))
        method_exchangeImplementations(swizzleImpl!, originalImpl!)
        print("swizzled")
    }
}

class MyWorkingViewController: InternalUIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
    }
}

InternalUIViewController.swizzle()

let obj = MyWorkingViewController()
obj.viewDidLoad()
*/