Xcode not calling application delegate after opting out of SceneDelegate - ios

Question

When iOS 13 released, I opted out of using the new SceneDelegate through the normal procedures.
- SceneDelegate.swift does no longer exist
- There are no Scene related methods in AppDelegate
- Application Scene Manifest is removed from .plist
This worked great, and is how I've been running since (iOS 11.0 target, Xcode 11.2.1).
Last week I ran a build with deployment target as 13.0, then swapped back to 11.0.
Since then, the application delegate methods are no longer being called, such as.
func application(_ application: UIApplication, open url: URL, options: [UIApplication.OpenURLOptionsKey : Any])
The only thing that happens, that I can see is a log in console
Can't end BackgroundTask: no background task exists with identifier 15 (0xf), or it may have already been ended
I've triple checked all the settings above, but I can't get it to work like it used to.
The only thing that might be different is that the storyboards now defaults to 'automatic' (iOS 13.0, *) presentation mode, but I'm not sure how it was before.
Since automatic is only available from iOS 13+, it seems like something is messed up.
Does anyone have a clue?
Following up on the response in this thread:
applicationDidBecomeActive
applicationWillEnterForeground
etc are actually called.
I've tried cleaning the build, restarting Xcode, the mac, the device, clearing derived data etc.

Answer 1

So, I finally found the answer.
Turns out it's a good old
Instance Method Nearly Matches
func application(_ application: UIApplication, continue userActivity: NSUserActivity,
restorationHandler: #escaping ([UIUserActivityRestoring]?) -> Void) -> Bool
func application(_ application: UIApplication, open url: URL, sourceApplication: String?, annotation: Any) -> Bool
That Xcode completely ignored to report, and somehow managed to break in between building for iOS 11 > iOS 13 > iOS 11.
It's also strange because I verified them a couple of days ago with the documentation, both Apples & Firebase, and there was no difference between them.
In the end, it works now, yay.

Answer 2

If you don't need want to use the SceneDelegate then add below property in the AppDelegate file.
var window: UIWindow?
Add this line above didFinishLaunchingWithOptions function
var window: UIWindow?
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool
{
// Override point for customization after application launch.
return true
}