Because I was unable to do it I tried hacking my way out of this situation. I read on the internet that in the previous version it was possible to use the UIKit legacy lifecycle, which in my case could be helping me solve my case. App launched but nothing happened and nothing printed in the console. I removed the SwiftUI App struct from the macOS target and tried adding the and to my AppDelegate implementation, but it resulted in the AppDelegate not being run at all. What I tried doing to have a complete control over what is happening with the window, is resigning from tag on the SwiftUI App struct and moving that to NSApplicationDelegate instance I coded. My Xcode version is 13.2.1 and macOS 12.1 I am using the latest SwiftUI and Xcode versions and probably can't downgrade, since I am on the new MacBook. What I find hard to do is using a custom NSWindow instance in combination with SwiftUI. It will be similar functionality to Cardhop, Fantastical and Harvest menubar apps.

In order to make the experience best for the user, apart from registering a menubar item I wanted to use a custom NSWindow instance that will be attached to a menubar item similarly to a NSPopover but will be able to detach when dragged outside and still maintain all the looks and feels of a normal NSWindow, like traffic light controls etc.

What I want to do is make the app on macOS a menu bar application. The application will share a lot of views and logic between iOS, iPadOS, watchOS and macOS. I am currently developing a SwiftUI app that I want to be cross-platform across majority of Apple devices (iPhone, watch, iPad, macOS).

Similar to cardhop