# isPackageKey The key for determining whether the resource is a file package. ``` static let isPackageKey: URLResourceKey ``` ## Discussion The system returns the value as a Boolean [`NSNumber`](/documentation/Foundation/NSNumber) object read-write in macOS 10.8 and later, and read-only in previous versions. A `true` value means that the resource is a file package. If you attempt to set or clear this key’s value on a file instead of a directory, the system ignores your attempt. If the directory as a package due to its filename extension or other reason apart from this key, setting this key’s value to `false` has no effect. --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)