---
title: "formIndex(after:)"
framework: swift
role: symbol
role_heading: Instance Method
path: "swift/flattensequence/formindex(after:)-7v0c1"
---

# formIndex(after:)

Replaces the given index with its successor.

## Declaration

```swift
func formIndex(after i: inout Self.Index)
```

## Parameters

- `i`: A valid index of the collection. i must be less than endIndex.