Re: how to make an object with a single unique instance like NSNull?
Re: how to make an object with a single unique instance like NSNull?
- Subject: Re: how to make an object with a single unique instance like NSNull?
- From: p3consulting <email@hidden>
- Date: Wed, 30 Mar 2005 20:56:49 +0200
Le 29 mars, 2005, à 16:48, Finlay Dobbie a écrit :
On Tue, 29 Mar 2005 09:42:22 -0500, Johnny Deadman
<email@hidden> wrote:
I need to make a version of NSNull for my own purposes (it has to be
a coredata* object so NSNull won't suffice) but I can't figure out
NSNull's trick of only having a single unique instance. In other words
[NSNull null]
always returns the same instance of NSNull no matter how many times
you call it.
How do I do this?
<http://developer.apple.com/documentation/Cocoa/Conceptual/
CocoaObjects/Articles/CreateSingleton.html>
Bug fix:
+ (id)allocWithZone:(NSZone *)zone
{
@synchronized(self) {
if (sharedGizmoManager == nil) {
sharedGizmoManager = [super allocWithZone:zone]; //
original version was: "return [super allocWithZone:zone];"
}
}
return sharedGizmoManager;
}
if not, calls to allocWithZone/alloc BEFORE any call to
+ (MyGizmoClass*)sharedManager
will return different objects...
Pascal Pochet
email@hidden
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