---
title: "add(_:)"
framework: foundation
role: symbol
role_heading: Instance Method
path: "foundation/nsmutableindexset/add(_:)-6zmti"
---

# add(_:)

Adds the indexes in an index set to the receiver.

## Declaration

```swift
func add(_ indexSet: IndexSet)
```

## Parameters

- `indexSet`: Index set to add.

## See Also

### Adding Indexes

- [add(_:)](foundation/nsmutableindexset/add(_:)-6dtkj.md)
- [add(in:)](foundation/nsmutableindexset/add(in:).md)