Avoid multiple instance creation of view controller

Question

I have a custom view controller in which I have created a custom navigation bar with multiple buttons.I have used that custom view controller as parent of multiple child controllers(to use that same navigation bar in multiple controllers).I am navigating to someController on some button click. The problem is, instance of that viewcontroller is created every time I clicked on that button.And when I am navigating back the same controller is presented.

This is action for menu button click:

@objc func showMenu(){
let storyBoard = UIStoryboard(name: "Main", bundle: nil)
let menuVC = storyBoard.instantiateViewController(withIdentifier: "MenuVC") as! MenuVC
if menuVC.view.window ==nil {
UIView.transition(with: self.view, duration: 0.5, options: .curveEaseIn,          animations: {
       self.present(menuVC, animated: true, completion: nil)
    })
} else {
    // view controller is visible
   }
}

This is the action for back button click:

@objc func  backBtnPressed(){
    self.dismiss(animated:true,complition:nil)
}

I tried viewController.view.window but the problem is new instance of baseViewController is created every time the button is pressed.How to avoid multiple instance creation?I am not using navigation controller.

How to know that controller is already presented in this scenario.

Answer 1

Create var menuVC variable as instance variable, not a local variable, then check like below for nil.

if menuVC != nil {
// use the created instance of menuVC
} else {
// create menuVC 
}

This way you have only one instance of menuVC. Please comment any doubt.