# version() Returns the version number assigned to the class. ``` class func version() -> Int ``` ## Return Value The version number assigned to the class. ## Discussion If no version has been set, the default is `0`. Version numbers are needed for decoding or unarchiving, so older versions of an object can be detected and decoded correctly. Caution should be taken when obtaining the version from within an `NSCoding` protocol or other methods. Use the class name explicitly when getting a class version number: ```objc version = [MyClass version]; ``` Don’t simply send `version` to the return value of class—a subclass version number may be returned instead. ### Special Considerations The version number applies to `NSArchiver`/`NSUnarchiver`, but not to `NSKeyedArchiver`/`NSKeyedUnarchiver`. A keyed archiver does not encode class version numbers. ## See Also --- 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)