Implement methods: retain, release, autorelease.

-(id)retain
{
NSIncrementExtraRefCount(self);
return self;
}

-(void)release
{
if(NSDecrementExtraRefCountWasZero(self))
{
NSDeallocateObject(self);
}
}

-(id)autorelease
{
// Add the object to the autorelease pool
[NSAutoreleasePool addObject:self];
return self;
}