Internal refCount for tracking object liveness in a way that avoids the object doing meaningful work when it's supposed to be dead/dying.

gistfile1.m

// Example ignores concurrency protection on internalRefCount for brevity.
// Not compatible with ARC, for obvious reasons (but could be implemented in part with a non-ARC category?).
@interface Foo ()

@property (nonatomic, assign) NSUInteger internalRefCount;

@end


@implementation Foo

- (instancetype)init;
{
    self = [super init];
    if (self) {
        _internalRefCount = 1;
    }
    return self;
}

- (id)retain;
{
    self.internalRefCount++;
}

- (oneway void)release;
{
    if (!--self.internalRefCount) {
        // Oh no! Dealloc is coming!
        [self release];
    }
}

@end