---
title: "index(_:ofObjectPassingTest:)"
framework: foundation
role: symbol
role_heading: Instance Method
path: "foundation/nsorderedset/index(_:ofobjectpassingtest:)"
---

# index(_:ofObjectPassingTest:)

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.

## Declaration

```swift
func index(_ opts: NSEnumerationOptions = [], ofObjectPassingTest predicate: (Any, Int, UnsafeMutablePointer<ObjCBool>) -> Bool) -> Int
```

## 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: The block returns a Boolean value that indicates whether obj passed the test.

## Return Value

Return Value The index whose corresponding value in the ordered set passes the test specified by predicate and opts.  If no objects in the ordered set  pass the test, returns NSNotFound.

## Discussion

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 and/or reverse as enumeration options to modify this behavior.

## See Also

### Accessing Set Members

- [contains(_:)](foundation/nsorderedset/contains(_:).md)
- [enumerateObjects(at:options:using:)](foundation/nsorderedset/enumerateobjects(at:options:using:).md)
- [enumerateObjects(_:)](foundation/nsorderedset/enumerateobjects(_:).md)
- [enumerateObjects(options:using:)](foundation/nsorderedset/enumerateobjects(options:using:).md)
- [firstObject](foundation/nsorderedset/firstobject.md)
- [lastObject](foundation/nsorderedset/lastobject.md)
- [object(at:)](foundation/nsorderedset/object(at:).md)
- [subscript(_:)](foundation/nsorderedset/subscript(_:).md)
- [objects(at:)](foundation/nsorderedset/objects(at:).md)
- [index(of:)](foundation/nsorderedset/index(of:).md)
- [index(of:inSortedRange:options:usingComparator:)](foundation/nsorderedset/index(of:insortedrange:options:usingcomparator:).md)
- [index(ofObjectAt:options:passingTest:)](foundation/nsorderedset/index(ofobjectat:options:passingtest:).md)
- [index(ofObjectPassingTest:)](foundation/nsorderedset/index(ofobjectpassingtest:).md)
- [indexes(ofObjectsAt:options:passingTest:)](foundation/nsorderedset/indexes(ofobjectsat:options:passingtest:).md)
- [indexes(ofObjectsPassingTest:)](foundation/nsorderedset/indexes(ofobjectspassingtest:).md)