macOS Zoom Button

As an application can have multiple windows, the function below will hide the zoom button on all windows, however you can filter out a specific window that you want to target if you choose.

func hideZoomButton() {
    for window in NSApplication.shared.windows {
        if let zoomButton = window.standardWindowButton(NSWindow.ButtonType.zoomButton) {
            zoomButton.isHidden = true
        }
    }
}

You can then call this function from you application delegate on applicationDidFinishLaunching