Fetch AXUIElement attribute's value from a given path

AXUtility_valueOfUIElement.m

/**
 * Fetch AXUIElement attribute's value from a given path
 * @attributePath           Parent-child path string
 *                          Example: "AXMenuBar"
 *                                   "AXFocusedWindow, AXDocument"
 *                                   "AXFocusedWindow, AXCloseButton, AXEdited"
 * @return                  see [self valueOfUIElement: attribute:]
 *
 * TRYME: reprototype to [self valueOfUIElement:(AXUIElementRef) attributePath:(NSString *) ...]
 */
+ (CFTypeRef _Nullable)valueOfUIElement:(AXUIElementRef _Nonnull)element attributePath:(nonnull NSString *)attributePath {
    AXError e = kAXErrorFailure;
    CFTypeRef value = NULL;
    CFTypeRef *heap = NULL;
    NSArray<NSString *> *list;
    NSUInteger sz;
    NSUInteger i;
    NSString *attr;

    ASSERT_NONNULL(element);
    ASSERT_NONNULL(attributePath);

    list = [attributePath componentsSeparatedByString:@","];
    sz = [list count];

    if (sz > 0) {
        if ((heap = (CFTypeRef *) malloc(sz * sizeof(CFTypeRef))) != NULL) {
            (void) memset(heap, 0, sz * sizeof(CFTypeRef));
        }
    }
    if (heap == NULL) goto out_exit;

    for (i = 0; i < sz; i++) {
        heap[i] = value;

        attr = [[list objectAtIndex:i] stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
        e = AXUIElementCopyAttributeValue(element, (__bridge CFStringRef) attr, &value);
        if (e != kAXErrorSuccess) {
            LOG_ERR("AXUIElementCopyAttributeValue() fail  attribute: %@ error: %@", attr, [self axErrorName:e]);
            break;
        }

        /* Stop when we met first non-AXUIElementRef value */
        if (CFGetTypeID(value) != AXUIElementGetTypeID()) {
            if (i != sz - 1) {
                LOG_ERR("Met non-AXUIElementRef value in the interim  idx: %lu attr: %@", i, attr);
                e = kAXErrorFailure;
            }
            break;
        }

        element = (AXUIElementRef) value;
    }

    /* Release interim AXUIElementRef */
    for (i = 0; i < sz; i++) {
        CFSafeRelease(heap[i]);
    }
    free(heap);

out_exit:
    return e == kAXErrorSuccess ? value : nil;
}

Test:

2019-02-22 21:03:38.371 office-badge[8638:158864] [DBG] >> Role:     AXApplication
2019-02-22 21:03:38.371 office-badge[8638:158864] [DBG] >> Document: file:///Users/lynnl/A.docx
2019-02-22 21:03:38.371 office-badge[8638:158864] [DBG] >> Edited:   1