A complete code.

Please use Code Block (shown as an icon < > with box below the editing area of Your Answer) when you show your code. And you should better not think a few hundred of lines as long, when readers say it is needed.

Seems you are using many third party frameworks. You should better contact the authors of them.

When I created a new file with File > New > File... > Cocoa Class > Class: MySecondWindowController, Subclass of NSWindowController, no XIP selected, I could choose Both MyWindowController and MySecondWindowController in the pull down list of Custom Class > Class of the Identity Inspector of the window controller. Not a subclass of NSViewController, it should be a subclass of NSWindowController. And you should go to step 2 after you completely copy my code into MyWindowController.swift, the order of the shown steps have meaning.

Are you sure you changed setupNowPlaying() to setupNowPlaying(artist: String, title: String, artwork: UIImage?) ? I tested my code before showing and unless you are doing something wrong, that sort of errors would never happen. Please check if you applied all the changes I have shown or show the full code of the view controller.

Generally, you should not include two or more topics in one thread. And in this case, I do not understand what you want to achieve. You should better start a new thread and clarify what you want to do.

Sorry, but I do not know much about that. You may start with searching airplay in the developer site.

@Matthias2349120, then the behavior is different than the result I tried with the iOS 15 Simulator -- iPhone 8 Plus/iOS 15.0 (19A339). Can you clarify the condition to reproduce the behavior you describe?

You are talking about something which deprecated in iOS 15.0. Are testing my code under the condition where iOS 15 feature is available? And I never proposed you to use UIButton.Configuration.filled(). Can you tell me if there are any descriptions of filled() in UIButton.Configuration?

Xcode 13.0 (12A233) does not contain macOS SDK 12.

Please do not ignore my comment: Are testing my code under the condition where iOS 15 feature is available?

my project is iOS 15 and is also Mac Catalyst. So I only have 1 code for iOS and macOS, no project settings switching. You should better include such an important info in the original post. Which version of Xcode are you using? Have you really set the DEPLOYMENT TARGET of both Project and Target to iOS 15/macOS 12? (If you are using the released version of Xcode 13, you cannot choose macOS 12.)

As far as I tried, .searchable does not work when it is embedded inside a TabView. You may try adding nested NavigationView, but it may cause other issues. Better re-consider the overall view structure or find another way than searchable.

You should better start a new thread, including enough code as text using Code Block.

Seems your check is not enough, longtitude is not longitude.