Swift - Accessing AppDelegate window from viewController - ios

Question

I make walkthrough (onboarding flow) in my app and I'd like to have a skip button.
The button is located on viewController, so I figured out that the best way to move to another viewController would be access app delegate window.
However, it keeps getting me an error that AppDelegate.Type does not have a member called "window".
#IBAction func skipWalkthrough(sender: AnyObject) {
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
AppDelegate.window!.rootViewController = RootViewController
}
Is there anything wrong with such approach?
Thanks in advance!

Answer 1

You have a typo it is supposed to be appDelegate not AppDelegate. So like this:
#IBAction func skipWalkthrough(sender: AnyObject) {
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
appDelegate.window!.rootViewController = RootViewController
}
Swift 3.2
#IBAction func skipWalkthrough(_ sender: AnyObject) {
let appDelegate = UIApplication.shared.delegate as! AppDelegate
appDelegate.window!.rootViewController = controller
}

Answer 2

This is for with or without Storyboard and it is working for Swift 3+
let appDelegate = UIApplication.shared.delegate as? AppDelegate
let mainStoryboard = UIStoryboard(name: "Main", bundle: nil)
let homeController = mainStoryboard.instantiateViewController(withIdentifier: "HomeViewController") as! HomeViewController
appDelegate?.window?.rootViewController = homeController

Answer 3

Swift 3
This is a better way:
if let window = NSApplication.shared().windows.first {
window.acceptsMouseMovedEvents = true;
}

Answer 4

appDelegate.window!.rootViewController is not working in Swift 5
Here is working code
Add below extension
extension UIWindow {
static var key: UIWindow! {
if #available(iOS 13, *) {
return UIApplication.shared.windows.first { $0.isKeyWindow }
} else {
return UIApplication.shared.keyWindow
}
}
}
use
let mainSB = UIStoryboard(name: "Main", bundle: nil)
if let RootVc = mainSB.instantiateViewController(withIdentifier: "NavigationController") as? UINavigationController{
UIWindow.key.rootViewController = RootVc
}
UIWindow.key // to access only window

Answer 5

You can also use conditional binding to reach the window.
if let window = UIApplication.shared.windows.first {
// use window here.
}

Answer 6

You are using the protocol name (i.e. AppDelegate) instead of the instance:
Should be:
appDelegate.window!.rootViewController = RootViewController

Answer 7

You can access tab bar anywhere from the app. Use below:
let appDelegate = UIApplication.shared.delegate as! AppDelegate
if let tabBarController = appDelegate.window!.rootViewController as? UITabBarController {
if let tabItems = tabBarController.tabBar.items {
let tabItem = tabItems[2]
tabItem.badgeValue = "5" //enter any value
}
}

Answer 8

This solution work for :
After Login / Register Programmatically add UITabbarController
let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
appDelegate.window!.rootViewController = tabs
appDelegate.window!.makeKeyAndVisible()