How to Properly Handle a Nil Uiapplication.Sharedapplication().Keywindow

How to properly handle a nil UIApplication.sharedApplication().keyWindow

Situation 1: - Manual UIWindow creation in App's delegate

You have probably somehow added a UIViewController to a UIWindow before setting it as key.

You should call window.makeKeyAndVisible() in your app's delegate after creating the window.

Situation 2: - Automatic storyboard instantiation

The system reads your storyboard, initializes the root view controller, prepares it by calling viewDidLoad and viewWillAppear, adds it to the window and shows the window.

What happens is the system cannot just set the window to the front and animate the view controller onto it, because it's the first view controller and you are not push/popping of a nav controller. And viewDidLoad can take some time... So the Default.png is showing in the meanwhile until the view controller is ready.

Then it calls viewDidAppear, when it has actually appeared. So that's where you should be able to access a keyWindow

Situation 3:

You are in a weird situation where you have windows but none of them is the "key" window currently, but you desperately need to access the window.

Call UIApplication.sharedApplication().windows, see if it's not empty and take the first element. UIApplication.sharedApplication().delegate?.window might have a value too, but it's usually only when the window is key already.

UIApplication sharedApplication - keyWindow is nil?

This code was executed before [window makeKeyAndVisible]; which is inside the app delegate.
So, no wonder why keyWindow was nil yet.

Proper way to pop to another ViewController from a TableViewCell

Had to be called from the root View Controller by UIApplication.sharedApplication().keyWindow?.rootViewController?.presentViewController(actionSheet, animated: true, completion: nil)

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