Get the top most viewController anywhere in the app (typically from the appDelegate). Get the current visible viewController.

topMostViewController.swift

extension UIViewController {
    func topMostViewController() -> UIViewController {
        if self.presentedViewController == nil {
            return self
        }
        if let navigation = self.presentedViewController as? UINavigationController {
            return navigation.visibleViewController.topMostViewController()
        }
        if let tab = self.presentedViewController as? UITabBarController {
            if let selectedTab = tab.selectedViewController {
                return selectedTab.topMostViewController()
            }
            return tab.topMostViewController()
        }
        return self.presentedViewController!.topMostViewController()
    }
}

extension UIApplication {
    func topMostViewController() -> UIViewController? {
        return self.keyWindow?.rootViewController?.topMostViewController()
    }
}

Thank you for this gist. Just a small note that visibleViewController is optional so it would be safer to do this:

 if let navigation = self.presentedViewController as? UINavigationController {
        if let visibleController = navigation.visibleViewController {
             return visibleController.topMostViewController()
        }
}

above one would not work cause you have to return something, you can use this instead on line 7 :
return navigation.visibleViewController?.topMostViewController() ?? navigation

extension UIViewController {
    func topMostViewController() -> UIViewController {
        
        if let presented = self.presentedViewController {
            return presented.topMostViewController()
        }
        
        if let navigation = self as? UINavigationController {
            return navigation.visibleViewController?.topMostViewController() ?? navigation
        }
        
        if let tab = self as? UITabBarController {
            return tab.selectedViewController?.topMostViewController() ?? tab
        }
        
        return self
    }
}

This is how to use this code:

let topMostViewController = UIApplication.shared.topMostViewController()

Thanks bud

extension UIViewController {
    func topMostViewController() -> UIViewController {
        
        if let presented = self.presentedViewController {
            return presented.topMostViewController()
        }
        
        if let navigation = self as? UINavigationController {
            return navigation.visibleViewController?.topMostViewController() ?? navigation
        }
        
        if let tab = self as? UITabBarController {
            return tab.selectedViewController?.topMostViewController() ?? tab
        }
        
        return self
    }
}

@bartleby Thank you sir.

i think need to add for pageviewcontroller related code

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

Since self.keywindow is deprecated in iOS 13.0, I changed extension like this.

extension UIApplication {
  func topMostViewController() -> UIViewController? {
    return UIApplication.shared.windows.filter { $0.isKeyWindow }.first?.rootViewController?.topMostViewController()
  }
}

thanks!

'windows' was deprecated in iOS 15.0, updated extension:

func topMostViewController() -> UIViewController? {
        
        let vc = UIApplication.shared.connectedScenes.filter {
            $0.activationState == .foregroundActive
        }.first(where: { $0 is UIWindowScene })
            .flatMap( { $0 as? UIWindowScene })?.windows
            .first(where: \.isKeyWindow)?
            .rootViewController?
            .topMostViewController()
        
        return vc
    }

extension UIViewController {
    
    func topMostViewController() -> UIViewController {
        if self.presentedViewController == nil {
            return self
        }
        
        if let navigation = self.presentedViewController as? UINavigationController {
            return navigation.visibleViewController!.topMostViewController()
        }
        
        if let tab = self.presentedViewController as? UITabBarController {
            if let selectedTab = tab.selectedViewController {
                return selectedTab.topMostViewController()
            }
            return tab.topMostViewController()
        }
        
        return self.presentedViewController!.topMostViewController()
    }
    
}

Tested with ios 15.4.1

@available(iOS 15.0, *)
var keyWindow:UIWindow? {
    let scene = UIApplication.shared.connectedScenes.filter({$0.activationState == .foregroundActive}).first as? UIWindowScene
    let keyWindow = scene?.keyWindow
    return keyWindow
}

@ielyas please, your code work with iPhone fine, but on iPad it returns vc : Fatal error: Unexpectedly found nil while unwrapping an Optional value
Any idea what's different for the iPad?