Re: 'Pseudo' Singleton in Objective C
Re: 'Pseudo' Singleton in Objective C
- Subject: Re: 'Pseudo' Singleton in Objective C
- From: Oliver Fuchs <email@hidden>
- Date: Thu, 14 Mar 2013 19:43:38 +0100
Hi,
Firstly, I'm assuming the more information button is the only location
which triggers displaying/redisplaying.
if thats the case I would just store the instance of your class in a property and make sure it will be created only once.
You can accomplish this by simply overwriting the getter method like this:
-(your class) foo {
if (!_foo) {
_foo = [[yourclass alloc]init];
}
return _foo;
}
be careful about mem managment. above is good for a retain property!
best regards,
oliver
Von meinem iPhone gesendet
Am 14.03.2013 um 19:22 schrieb Pax <email@hidden>:
> 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 - but that's not the right answer because it means that I can't release information window and its class when it gets closed, resulting in a minor leak (only minor because, as a singleton, the instance is only ever loaded once anyway). Even so, this is one leak too many - and I'be grateful if someone could tell me the correct way to do what I am trying to do.
>
> Currently, I am setting to be a singleton as follows:
>
> static informationWindow *singletonManager = nil;
>
> @implementation informationWindow
>
> //Code to handle singleton
> + (id)singleton
> {
> @synchronized(self)
> {
> if(singletonManager == nil)
> singletonManager = [[super allocWithZone:NULL] init];
> }
> return singletonManager;
> }
>
> + (id)allocWithZone:(NSZone *)zone
> {
> return [[self singleton] retain];
> }
>
> - (id)copyWithZone:(NSZone *)zone
> {
> return self;
> }
>
> - (id)retain
> {
> return self;
> }
>
> - (unsigned)retainCount
> {
> return UINT_MAX;
> }
>
> - (oneway void)release
> {
>
> }
>
> - (id)autorelease
> {
> return self;
> }
>
>
> I'm not using ARC. All suggestions gratefully received!
>
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