# indexes(options:ofObjectsPassingTest:) Returns the index of an object in the ordered set that passes a test in a given block for a given set of enumeration options. ``` func indexes(options opts: NSEnumerationOptions = [], ofObjectsPassingTest predicate: (Any, Int, UnsafeMutablePointer) -> Bool) -> IndexSet ``` ## Parameters `opts` A bitmask that specifies the options for the enumeration (whether it should be performed concurrently and whether it should be performed in reverse order). `predicate` The block to apply to elements in the ordered set. The block takes three arguments: - obj: The element in the ordered set. - Term: The index of the element in the ordered set. - stop: A reference to a Boolean value. The block can set the value to to stop further processing of the set. The `stop` argument is an out-only argument. You should only ever set this value to within the block. ## Return Value The index whose corresponding value in the ordered set passes the test specified by `predicate` and `opts`. If the `opts` bitmask specifies reverse order, then the last item that matches is returned. Otherwise, the index of the first matching object is returned. If no objects in the ordered set pass the test, returns `NSNotFound`. ## Discussion By default, the enumeration starts with the first object and continues serially through the ordered set to the last object. You can specify [`concurrent`](/documentation/Foundation/NSEnumerationOptions/concurrent) and/or [`reverse`](/documentation/Foundation/NSEnumerationOptions/reverse) as enumeration options to modify this behavior. > Important: > If the block parameter or `s` is `nil`, this method raises an exception. --- 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)