makeFirstResponder does not always fire

I have an NSSearchField inside a NSToolbar that I am attempting to set makeFirstResponder on but it is working intermittently. At times the NSSearchField will become the first responder without the call to makeFirstResponder and makeFirstResponder is returning true as if it were set successfully. Setting NSWindow.initialFirstResponder has also failed to work.

class ViewController: NSViewController {
    override func viewDidAppear() {
        super.viewDidAppear()
        view.window?.makeFirstResponder(view.window?.windowController?.searchField
    }
}

I have had consistent working results by delaying the code with a timer but this is a less than ideal solution.

class ViewController: NSViewController {
    override func viewDidAppear() {
        super.viewDidAppear()
        Timer.scheduledTimer(withTimeInterval: 1, repeats: false) { _ in
            self.view.window?.makeFirstResponder(self.windowController?.searchField)
        }
    }
}

I found a blog that led me to find the reason why this was happening. By default in macOS an NSWindow has an isRestorable Boolean value that will recall whatever the last firstResponder was regardless of what is set as an initialFirstResponder or what is set inside viewDidAppear, etc.