A potential replacement for NSHashTable for iOS 5 - need to test it and see how it works with ARC.

SthToTest

/* Source: http://stackoverflow.com/questions/4692161/non-retaining-array-for-delegates/4692229#4692229 */

@implementation NSMutableArray (WeakReferences)

+ (id)mutableArrayUsingWeakReferences
{
    return [self mutableArrayUsingWeakReferencesWithCapacity:0];
}

+ (id)mutableArrayUsingWeakReferencesWithCapacity:(NSUInteger)capacity {
    CFArrayCallBacks callbacks = {0, NULL, NULL, CFCopyDescription, CFEqual};
    
    // We create a weak reference array
    return (id)(CFArrayCreateMutable(0, capacity, &callbacks));
}

@end