How to communicate to the window controller from view controller of newly, programmatically created tab? - swift

Question

In my window controller, I implement:
#IBAction override func newWindowForTab(_ sender: Any?) {
if let wc = NSStoryboard.main?.instantiateInitialController() as? WindowController,
let window = wc.window {
self.window?.addTabbedWindow(window, ordered: .above)
window.makeKey()
}
}
In the view controller, I have this code:
let window = self.view.window?.windowController as? WindowController
Also tried:
let window = NSApp.mainWindow?.windowController as? WindowController
If I don't have any tabs, it's able to get the window controller. But on new tabs, it does grab the window controller.
Similarly, I've unsuccessfully tried sending an action to the WindowController:
NSApp.sendAction(#selector(WindowController.pageLabelChange), to: nil, from: label)
Works for the original window, but not for any newly created tabs.
How do the newly created view controller objects communicate with the window controller?
Edit:
For more context in how I am using this code: It's basically a PDFView that's embedded in a window. The window has a tool bar that displays the page number. Using any of the above code, I can set the current page number of the PDFView, but when there's a tab, it does not work. Using the .PDFViewPageChanged notification, I call my func
NSApp.sendAction(#selector(WindowController.pageLabelChange), to: nil, from: pdfView)
Edit 2:
I've created a GitHub with a test project that shows the problem I have. You should be able to see that when you launch the project, the + button will add a number to the textfield in the tab bar. But if you go to the View menu > Add tab, it creates a new tab, but the + does nothing.

Answer 1

You create new window controller on stack so it is destroyed right after return, that is the reason. You need to store somewhere reference to created tab window controller and manage it (the place of storage is up to your app logic).
Here is simple demo that makes code work
Tested with Xcode 11.4 / macOS 10.15.5
final class WindowController: NSWindowController {
#IBOutlet weak var testField: NSTextField!
var tabControllers = [WindowController]() // << storage for child controllers
#IBAction override func newWindowForTab(_ sender: Any?) {
if let wc = NSStoryboard.main?.instantiateInitialController() as? WindowController,
let window = wc.window {
self.window?.addTabbedWindow(window, ordered: .above)
window.makeKey()
tabControllers.append(wc) // keep reference in storage
// TODO: - you are responsible to manage wc, eg: remove
// from storage on window close.
}
}
}