---
title: "shiftIndexesStarting(at:by:)"
framework: foundation
role: symbol
role_heading: Instance Method
path: "foundation/nsmutableindexset/shiftindexesstarting(at:by:)"
---

# shiftIndexesStarting(at:by:)

Shifts a group of indexes to the left or the right within the receiver.

## Declaration

```swift
func shiftIndexesStarting(at index: Int, by delta: Int)
```

## Parameters

- `index`: Head of the group of indexes to shift.
- `delta`: Amount and direction of the shift. Positive integers shift the indexes to the right. Negative integers shift the indexes to the left.

## Discussion

Discussion The group of indexes shifted is made up by index and the indexes that follow it in the set. A left shift deletes the indexes in a range the length of delta preceding index from the set. A right shift inserts empty space in the range (``index``,``delta``) in the receiver. The resulting indexes must all be in the range 0 .. NSNotFound - 1.