# decodeTopLevelObjectOfClasses:forKey:error: Decode an object as one of several expected types, failing if the archived type does not match. ``` - (id) decodeTopLevelObjectOfClasses:(NSSet *) classes forKey:(NSString *) key error:(NSError **) error; ``` ## Parameters `classes` A set of expected classes that the object being decoded should match at least one of. `key` The archive key indicating the member to decode. `error` On return, an [`NSError`](/documentation/Foundation/NSError) indicating why decoding failed, or `nil` if no error occurred. ## Return Value The decoded object, or `nil` if decoding fails. ## Discussion This method is equivalent to [`decodeObject(of:forKey:)`](/documentation/Foundation/NSCoder/decodeObject(of:forKey:)-roif), but allows you to specify a set of classes that the decoded object can match. If [`requiresSecureCoding`](/documentation/Foundation/NSCoder/requiresSecureCoding) is , the decoded object’s class must be a member of the classes parameter, or a sublcass of a member. --- 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)