Find the current top view controller for your iOS application

gistfile1.m

- (UIViewController *)topViewController{
  return [self topViewController:[UIApplication sharedApplication].keyWindow.rootViewController];
}

- (UIViewController *)topViewController:(UIViewController *)rootViewController
{
  if (rootViewController.presentedViewController == nil) {
    return rootViewController;
  }
  
  if ([rootViewController.presentedViewController isMemberOfClass:[UINavigationController class]]) {
    UINavigationController *navigationController = (UINavigationController *)rootViewController.presentedViewController;
    UIViewController *lastViewController = [[navigationController viewControllers] lastObject];
    return [self topViewController:lastViewController];
  }
  
  UIViewController *presentedViewController = (UIViewController *)rootViewController.presentedViewController;
  return [self topViewController:presentedViewController];
}

My ver to find topViewController with SSASideMenu

public extension UIApplication {

public class func topViewController(_ base: UIViewController? = UIApplication.shared.keyWindow?.rootViewController) -> UIViewController? {
    if let SSASide = base as? SSASideMenu {
        if let nav = SSASide.contentViewController as? UINavigationController{
        return topViewController(nav.visibleViewController)
        }
    }
    if let nav = base as? UINavigationController {
        return topViewController(nav.visibleViewController)
    }
    
    if let tab = base as? UITabBarController {
        let moreNavigationController = tab.moreNavigationController
        
        if let top = moreNavigationController.topViewController, top.view.window != nil {
            return topViewController(top)
        } else if let selected = tab.selectedViewController {
            return topViewController(selected)
        }
    }
    
    if let presented = base?.presentedViewController {
        return topViewController(presented)
    }
    
    return base
}

I like mohammadshalhoob's version because it takes moreNavigationController into account. However, I found that moreNavigationController.topViewController.view.window != nil didn't work as intended when used in viewWillAppear, before the view is attached to the window. To test whether the sixth or more view controller is selected, I just used tab.selectedIndex > 4.

I'm curious where UIViewController's children has gone?