replaceImageFileNamesWithUUIDs

- (void)replaceFileNamesOfImagesWithUUIDsAtPath:(NSString *)path {
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSURL *directoryURL = [NSURL fileURLWithPath:path];
    NSArray *keys = [NSArray arrayWithObject:NSURLIsDirectoryKey];
    
    NSDirectoryEnumerator *enumerator = [fileManager
                                         enumeratorAtURL:directoryURL
                                         includingPropertiesForKeys:keys
                                         options:0
                                         errorHandler:^(NSURL *url, NSError *error) {
                                             // Handle the error.
                                             // Return YES if the enumeration should continue after the error.
                                             return YES;
                                         }];
    
    for (NSURL *url in enumerator) {
        NSError *error;
        NSNumber *isDirectory = nil;
        if (! [url getResourceValue:&isDirectory forKey:NSURLIsDirectoryKey error:&error]) {
            // handle error
        }
        else if (! [isDirectory boolValue]) {
            if ([url.pathExtension isEqualToString:@"png"]) {
                NSLog(@"%@", url.path);
                NSString *uuid = [[NSUUID UUID] UUIDString];
                [[NSFileManager defaultManager] moveItemAtPath:url.path toPath:[path stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.png", uuid]] error:nil];
            }
        }
    }
}