# setObject Adds an object to the OSOrderedSet if it is not already present, storing it in sorted order if there is an order function. ``` bool setObject(const OSMetaClassBase *anObject); ``` ## Parameters `anObject` The OSMetaClassBase-derived object to be added to the ordered set. ## Return Value `true` if `anObject` was successfully added to the ordered set, `false` otherwise (including if it was already in the ordered set). ## Discussion The set adds storage to accomodate the new object, if necessary. If successfully added, the object is retained. If `anObject` is not already in the ordered set and there is an order function, this function loops through the existing objects, calling the order function with arguments each existingObject, `anObject`, and the ordering context (or `NULL` if none was set), until the order function returns a value *greater than* or equal to 0. It then inserts `anObject` at the index of the existing object. If there is no order function, the object is inserted at index 0. A `false` return value can mean either that `anObject` is already present in the set, or that a memory allocation failure occurred. If you need to know whether the object is already present, use containsObject(const OSMetaClassBase *). --- 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)