# indexes(ofObjectsAt:options:passingTest:) Returns the index, from a given set of indexes, of the object in the ordered set that passes a test in a given block for a given set of enumeration options. ``` func indexes(ofObjectsAt s: IndexSet, options opts: NSEnumerationOptions = [], passingTest predicate: (Any, Int, UnsafeMutablePointer) -> Bool) -> IndexSet ``` ## Parameters `s` The indexes of the objects over which to enumerate. `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. - idx: 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. The block returns a Boolean value that indicates whether `obj` passed the test. ## Return Value The index of the corresponding value in the ordered set that passes the test specified by predicate. 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 will raise 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)