Using Stack DFS to optimize file recursion (Objective C)

DeleteFiles.m

- (void)mnz_removeFolderContentsRecursivelyAtPath:(NSString *)folderPath forItemsExtension:(NSString *)itemsExtension {
    NSArray *directoryContentsArray = [self contentsOfDirectoryAtPath:folderPath error:nil];
    NSString *currentPath = folderPath;
    NSEnumerator *enumerator = [directoryContentsArray objectEnumerator];
    NSMutableArray *stack = [NSMutableArray array];
    
    if (enumerator) {
        [stack addObject:enumerator];
    }
    
    /*
     Using Stack Depth-First-Search(DFS) to replace normal recursion
     Memory allocation can't be released asap in normal recursion way, so
     here is using local stack to maintain enumerators(pointers) to avoid
     high space complexity.
     */
    while([stack count] > 0) {
        NSEnumerator *top = stack.lastObject;
        NSString *fileName = [top nextObject];
        
        if (fileName) {
            NSDictionary *attributesDictionary = [self attributesOfItemAtPath:[currentPath stringByAppendingPathComponent:fileName] error:nil];
            
            if ([attributesDictionary objectForKey:NSFileType] == NSFileTypeDirectory) {
                currentPath = [currentPath stringByAppendingPathComponent:fileName];
                NSArray *contents = [self contentsOfDirectoryAtPath: currentPath error:nil];
                NSEnumerator *enumerator = [contents objectEnumerator];
                
                if (enumerator) {
                    [stack addObject:enumerator];
                }
            } else {
                if ([fileName.pathExtension.lowercaseString isEqualToString:itemsExtension]) {
                    [self mnz_removeItemAtPath:[currentPath stringByAppendingPathComponent:fileName]];
                }
            }
        } else {
            NSArray *contents = [self contentsOfDirectoryAtPath:currentPath error:nil];
            
            if (contents.count == 0 && currentPath != folderPath) {
                [self mnz_removeItemAtPath:currentPath];
            }
            
            currentPath = [currentPath stringByDeletingLastPathComponent];
            [stack removeLastObject];
        }
    }
}