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SceneDelegate Lifecycle
Introduction to SceneDelegate Lifecycle methods. What is extracted from AppDelegate
Introduction
In previous articles we have explained the AppDelegate function and lifecycle methods. Now we will explain what responsibility SceneDelegate and what responsibilities are extracted from AppDelegate.
Before iOS13 and xcode11, creating a project would result by default to have a file AppDelegate, UIViewController, storyboard and couple more files. In contrast, now you will also see a file SceneDelegate. AppDelegate is still created and it is still the main entry point for applications. SceneDelegate extract from it the responsibility to handle what is shown on screen, manage the lifecycle events of the instance of your apps user interface. It adding the option for multi window support. The trigger for multi window support is in the Info.plist in Application Scene Manifest(look at the image on the bottom of the article).
AppDelegate
application(_:didFinishLaunchingWithOptions:)
This method still handles all what we have mentioned in the previous article.
Initialise some 3rd party frameworks, initialise CoreData or any Storage etc.
Only exception is that now creating a window and to initialise the first screen is not the right place any more. It is moved to SceneDelegate.
application(_:configurationForConnecting:options:)
Retrieves the configuration data for UIKit to use when creating a new scene. Implement this method if you do not include scene-configuration data in your apps Info.plist file, or if you want to alter the scene configuration data dynamically.
Runes ones when you start the app. If relaunch the app the windows from the previous run will be restored. If it is not implemented it will fallback to the scene from Info.plist manifest.
application(_:didDiscardSceneSessions:)
Tells the delegate that the user closed one or more of the apps scenes from the app switcher.
