TopMostViewController+Extension.swift

//
//  TopMostViewController+Extension.swift
//
//  Created by Augus on 9/26/15.
//  Copyright © 2015 iAugus. All rights reserved.
//

import UIKit

/**
 Description: the toppest view controller of presenting view controller
 How to use: UIApplication.topMostViewController()
 Where to use: controllers are not complex
*/

extension UIApplication {
    class func topMostViewController() -> UIViewController? {
        var topController = UIApplication.sharedApplication().keyWindow?.rootViewController
        while topController?.presentedViewController != nil {
            topController = topController?.presentedViewController
        }
        return topController
    }
    
}


/**
 Description: the toppest view controller of presenting view controller
 How to use:  UIApplication.sharedApplication().keyWindow?.rootViewController?.topMostViewController()
 Where to use: There are lots of kinds of controllers (UINavigationControllers, UITabbarControllers, UIViewController)
*/

extension UIViewController {
    func topMostViewController() -> UIViewController? {
        // Handling Modal views
        if let presentedViewController = self.presentedViewController {
            return presentedViewController.topMostViewController()
        }
            // Handling UIViewController's added as subviews to some other views.
        else {
            for view in self.view.subviews
            {
                // Key property which most of us are unaware of / rarely use.
                if let subViewController = view.nextResponder() {
                    if subViewController is UIViewController {
                        let viewController = subViewController as! UIViewController
                        return viewController.topMostViewController()
                    }
                }
            }
            return self
        }
    }
}

extension UITabBarController {
    override func topMostViewController() -> UIViewController? {
        return self.selectedViewController?.topMostViewController()
    }
}

extension UINavigationController {
    override func topMostViewController() -> UIViewController? {
        return self.visibleViewController?.topMostViewController()
    }
}