On Mar 14, 2013, at 11:22 AM, Pax wrote:
> I don't really know how to describe what I'm trying to do except as a
> 'Pseudo' Singleton. I have a class with an NSWindow, which displays
> information. It is run by selecting an NSMenuItem called 'More Information…'
>
> My issue is that I only want one instance of the Information class to be
> loaded at a given time (and therefore only one information window on screen
> at a given time). If the information window is already loaded and it is then
> reselected from the menu then the existing window needs to be brought to the
> front - nothing more.
>
> I have currently resolved it by making my class a singleton…
I don't see anything to "resolve" so for the sake of clarification…
There's no reason to make your class a singleton just because you only want one
instance of it. Just don't create a second instance if you already have one.
Your "More Information" menu item is hooked up to some controller already —
presumably the application delegate. All that controller has to do is maintain
and reuse a reference to your InformationWindow.
> … but that's not the right answer because it means that I can't release
> information window…
Right. This is the reason you don't want a singleton or "pseudo" singleton.
There's no fancy pattern needed:
- (IBAction)showInformation:(id)sender
{
if (!_infoWindowController) {
_infoWindowController = [[InformationWindowController alloc]
init];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:@selector(infoWindowWillClose:) name:NSWindowWillCloseNotification
object:_infoWindowController.window];
}
[_infoWindowController showWindow:nil];
}
- (void)infoWindowWillClose:(NSNotification *)notification;
{
[[NSNotificationCenter defaultCenter] removeObserver:self
name:NSWindowWillCloseNotification object:_infoWindowController.window];
[_infoWindowController autorelease];
_infoWindowController = nil;
}
--
Seth Willits
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