iPhone — How to find topmost view controller

Question

I've run into a couple of cases now where it would be convenient to be able to find the "topmost" view controller (the one responsible for the current view), but haven't found a way to do it.

Basically the challenge is this: Given that one is executing in a class that is not a view controller (or a view) [and does not have the address of an active view] and has not been passed the address of the topmost view controller (or, say, the address of the navigation controller), is it possible to find that view controller? (And, if so, how?)

Or, failing that, is it possible to find the topmost view?

Answer 1

Here is what worked for me.

I found that sometimes the controller was nil on the key window, as the keyWindow is some OS thing like an alert, etc.

 + (UIViewController*)topMostController
 {
     UIWindow *topWndow = [UIApplication sharedApplication].keyWindow;
     UIViewController *topController = topWndow.rootViewController;

     if (topController == nil)
     {
         // The windows in the array are ordered from back to front by window level; thus,
         // the last window in the array is on top of all other app windows.
         for (UIWindow *aWndow in [[UIApplication sharedApplication].windows reverseObjectEnumerator])
         {
             topController = aWndow.rootViewController;
             if (topController)
                 break;
         }
     }

     while (topController.presentedViewController) {
         topController = topController.presentedViewController;
     }

     return topController;
 }

Answer 2

you could find the top most view controller by using

NSArray *arrViewControllers=[[self navigationController] viewControllers];
UIViewController *topMostViewController=(UIViewController *)[arrViewControllers objectAtIndex:[arrViewControllers count]-1];

Answer 3

Another solution relies on the responder chain, which may or may not work depending on what the first responder is:

1. Get the first responder.
2. Get the UIViewController associated with that first responder.

Example pseudo code:

+ (UIViewController *)currentViewController {
    UIView *firstResponder = [self firstResponder]; // from the first link above, but not guaranteed to return a UIView, so this should be handled more appropriately.
    UIViewController *viewController = [firstResponder viewController]; // from the second link above
    return viewController;
}

Answer 4

@implementation UIWindow (Extensions)

- (UIViewController*) topMostController
{
    UIViewController *topController = [self rootViewController];

    while (topController.presentedViewController) {
        topController = topController.presentedViewController;
    }

    return topController;
}

@end

Answer 5

For latest Swift Version:
Create a file, name it UIWindowExtension.swift and paste the following snippet:

import UIKit

public extension UIWindow {
    public var visibleViewController: UIViewController? {
        return UIWindow.getVisibleViewControllerFrom(self.rootViewController)
    }

    public static func getVisibleViewControllerFrom(vc: UIViewController?) -> UIViewController? {
        if let nc = vc as? UINavigationController {
            return UIWindow.getVisibleViewControllerFrom(nc.visibleViewController)
        } else if let tc = vc as? UITabBarController {
            return UIWindow.getVisibleViewControllerFrom(tc.selectedViewController)
        } else {
            if let pvc = vc?.presentedViewController {
                return UIWindow.getVisibleViewControllerFrom(pvc)
            } else {
                return vc
            }
        }
    }
}

func getTopViewController() -> UIViewController? {
    let appDelegate = UIApplication.sharedApplication().delegate
    if let window = appDelegate!.window {
        return window?.visibleViewController
    }
    return nil
}

Use it anywhere as:

if let topVC = getTopViewController() {

}

Answer 6

This is an improvement to Eric's answer:

UIViewController *_topMostController(UIViewController *cont) {
    UIViewController *topController = cont;

    while (topController.presentedViewController) {
        topController = topController.presentedViewController;
    }

    if ([topController isKindOfClass:[UINavigationController class]]) {
        UIViewController *visible = ((UINavigationController *)topController).visibleViewController;
        if (visible) {
            topController = visible;
        }
    }

    return (topController != cont ? topController : nil);
}

UIViewController *topMostController() {
    UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;

    UIViewController *next = nil;

    while ((next = _topMostController(topController)) != nil) {
        topController = next;
    }

    return topController;
}

_topMostController(UIViewController *cont) is a helper function.

Now all you need to do is call topMostController() and the top most UIViewController should be returned!