How do I check if an UIViewController is currently being displayed?

Question

How do I check if an UIViewController is currently being displayed?

My UIViewControllers are listening for NSNotifications - e

Answer 1

Specify title to each ViewController and then get the title of current ViewController by the code given bellow.

NSString *currentController = self.navigationController.visibleViewController.title;

Then check it by your title like this

if([currentController isEqualToString:@"myViewControllerTitle"]){

    //write your code according to View controller. 

}

Answer 2

Why don't you remove the notification listener in viewWillDisappear and add it in viewWillAppear?

Edit: misread his question, sorry.

Suggested answer: set your own flag (BOOL) in viewDidDisappear and viewDidAppear.

Answer 3

You can use flags in viewWillAppear and viewWillDisappear methods for this.

Answer 4

I think that checking of viewController.view.superview should works.

Answer 5

You need to check if your viewcontroller is on top of the stack of navigationcontroller's viewcontroller array. A sample code is,

if (self.navigationController.topViewController == self) {
    //the view is currently displayed
}

You can use this inside the viewWillAppear method to check whether the current view is visible.

Answer 6

It's too late to replay on this question.

To check the instance of a UIViewController is currently on the top of the screen or to check if it is showing on screen, you can put a check like:

// Get the topmost view showing on the screen as below
    UIViewController * currentVC = ((UINavigationController*)app.window.rootViewController).visibleViewController;

// Now check whether the viewcontroller you want to show is the same as the currently showing view controller.
    if (currentVC.class == myVC.class) {  // Here myVC is any/new instance of the viewcontroller you would like to check or show (if not shown).
         // If both are same then it returns true and executes this block of code.
    }