Collections of zeroing weak references under ARC

Question

How can I get an array of zeroing weak references under ARC? I don\'t want the array to retain the objects. And I\'d like the array elements either to remov

Answer 1

Just add a category for NSMutableSet with following code:

@interface WeakReferenceObj : NSObject
@property (nonatomic, weak) id weakRef;
@end

@implementation WeakReferenceObj
+ (id)weakReferenceWithObj:(id)obj{
    WeakReferenceObj *weakObj = [[WeakReferenceObj alloc] init];
    weakObj.weakRef = obj;
    return weakObj;
}
@end

@implementation NSMutableSet(WeakReferenceObj)
- (void)removeDeallocRef{
    NSMutableSet *deallocSet = nil;
    for (WeakReferenceObj *weakRefObj in self) {
        if (!weakRefObj.weakRef) {
            if (!deallocSet) {
                deallocSet = [NSMutableSet set];
            }
            [deallocSet addObject:weakRefObj];
        }
    }
    if (deallocSet) {
        [self minusSet:deallocSet];
    }
}

- (void)addWeakReference:(id)obj{
    [self removeDeallocRef];
    [self addObject:[WeakReferenceObj weakReferenceWithObj:obj]];
}
@end

Same way to create a category for NSMutableArray and NSMutableDictionary.

Remove dealloc reference in didReceiveMemoryWarning will be better.

- (void)didReceiveMemoryWarning{
    [yourWeakReferenceSet removeDeallocRef];
}

Then, what you should do is to invoke addWeakReference: for your container class.