How can I track opening and closing event of NSWindow? - cocoa

Question

I did try – windowDidExpose: but it didn't work. What do I have to try for this?
My window is a utility window.
-- edit for more clarity --
What I want are:
viewWillAppear
viewWillDisappear
viewDidLoad
viewDidUnload
in Cocoa Touch.

Answer 1

Very old question, but only for documentation purpose:
Track open:
In your windows controller override the method:
-(void)showWindow:(id)sender
{
//add this for track the window close
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(windowWillClose)
name:NSWindowWillCloseNotification
object:nil];
[super showWindow:sender];
//do here what you want...
}
Track close:
Implement the method
-(void)windowWillClose
{
[[NSNotificationCenter defaultCenter] removeObserver:self];
//do here what you want...
}

Answer 2

There is windowDidClose:, but that probably only refers to closing; if you're sending your window an orderOut: message, I don't think that counts.
You probably need to either just track it from whatever code you're ordering the window in and out from, or subclass the window's class and override methods like makeKeyAndOrderFront: and orderOut: (whatever you're using, at least) to post custom notifications before calling up to super.

Answer 3

For Swift
Track open: In your windows controller override the method:
override func showWindow(sender: AnyObject?) {
NSNotificationCenter.defaultCenter().addObserver(self, selector: #selector(windowWillClose), name: NSWindowWillCloseNotification, object: nil)
}
Track close: Implement the method:
func windowWillClose() -> Void {
NSNotificationCenter.defaultCenter().removeObserver(self);
//Do here what you want..
}

Answer 4

I came up with a hack for dealing with this. There is no notification that signals that a window has been put on screen, but there's a notification that's pretty much guaranteed to be sent when a window is put on screen. I'm speaking of NSWindowDidUpdateNotification, which indicates that a window has refreshed itself.
Of course, it's not only sent when the window appears—it's sent every time the window updates. Needless to say, this notification is sent a lot more than once. So you want to watch for it the first time, do your thing, and ignore any subsequent notifications. In my case, I wanted to add a sheet to a window that another part of my app would order in later. So I did something like this:
__block id observer = [NSNotificationCenter.defaultCenter addObserverForName:NSWindowDidUpdateNotification object:window queue:nil usingBlock:^(NSNotification *note) {
[self showSetupSheet];
[NSNotificationCenter.defaultCenter removeObserver:observer];
}];
There's no particular reason you would have to use a block-based observer—a method-based observer would work just as well.