How to safely store objects in extra within countByEnumeratingWithState under ARC?

Question

How can I safely store a couple object instances in NSFastEnumerationState's extra array?

I want these items to be retained while the loop is running, then released when the loop is complete.

- (NSUInteger)countByEnumeratingWithState: (NSFastEnumerationState *)state
                                  objects: (__unsafe_unretained id *)stackbuf
                                    count: (NSUInteger)len {
    unsigned long days = 0;
    id current = nil;
    id components = nil;
    if (state->state == 0)
    {
        current = [NSCalendar currentCalendar];
        state->mutationsPtr = &state->extra[0];
        components = [current components: NSDayCalendarUnit fromDate: _startDate toDate: _endDate options: 0];
        days = [components day];
        state->extra[0] = days;
        state->extra[1] = (uintptr_t)(__bridge void *)current;
        state->extra[2] = (uintptr_t)(__bridge void *)components;
    } else {
        days = state->extra[0];
        current = (__bridge NSCalendar *)(void *)(state->extra[1]);
        components = (__bridge NSDateComponents *)(void *)(state->extra[2]);
    }
    NSUInteger count = 0;
    if (state->state <= days) {
        state->itemsPtr = stackbuf;
        while ( (state->state <= days) && (count < len) ) {
            [components setDay: state->state];
            stackbuf[count] = [current dateByAddingComponents: components toDate: _startDate options: 0];
            state->state++;
            count++;
        }
    }
    return count;
}

Here's the definition of NSFastEnumerationState, from Apple's headers:

typedef struct {
    unsigned long state;
    id __unsafe_unretained *itemsPtr;
    unsigned long *mutationsPtr;
    unsigned long extra[5];
} NSFastEnumerationState;

Answer 1

Steven,

Why are you trying to use a C-language structure to hold these items rather than just make them private ivars in the class for which you are building an enumerator? Make them ivars and the problem just doesn't exist.

Andrew