How to check viewcontroller is added in stack or not

Question

I have two view controllers. I have navigated from one view to another view by press the button to using below code.

 *let secondViewController = self.storyboard!.instantiateViewControllerWithIdentifier("NotificationController") as! NotificationController  self.navigationController!.pushViewController(secondViewController, animated: true)* 

For the back, I am using bar button on bar button click for back using below code.

 self.navigationController?.popViewControllerAnimated(true) 

So my problem is if I am going from one view to another view continuously then it added in a stack. I want to only show another view when it is already added to the stack to stop adding it.It only adds one time.

Answer 1

To check whether the navigation stack contains a particular type of view controller, you can use:

if let viewControllers = self.navigationController?.viewControllers {     if viewControllers.contains(where: {         return $0 is YourViewController     })     {         //Write your code here     } } 

To remove a particular controller from navigation stack, you need to make changes to the navigation stack.

Example:

    if var viewControllers = self.navigationController?.viewControllers     {         for controller in viewControllers         {             if controller is UIViewController             {                 viewControllers.removeElement(controller)                 self.navigationController?.viewControllers = viewControllers             }         }     } 

Answer 2

For swift 4 you can use

 if let viewControllers = self.navigationController?.viewControllers {        for vc in viewControllers {             if vc.isKind(of: YourViewController.classForCoder()) {                  print("It is in stack")                  //Your Process             }        }  }