3-phase app startup pattern

AppDelegate.swift

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
        doPreUISetup()
        doWindowSetup()
	doPostUISetup()
        
        return true
    }

    func doPreUISetup() {
	//place code here that is required for app startup, especially anything the UI might rely on:
	//  setup/clear caches
	//  start logging
	//  etc.
    }

    func doWindowSetup() {
	//create and set root VC, if doing so programmatically
    }

    func doPostUISetup() {
	//place code here that doesn't rely on the UI:
	//  prefetching
	//  notification observer registration
	//  etc.
    }