# index(_:offsetBy:) Returns an index that is the specified distance from the given index. ``` func index(_ i: Self.Index, offsetBy distance: Self.Index.Stride) -> Self.Index ``` ## Parameters `i` A valid index of the collection. `distance` The distance to offset `i`. ## Return Value An index offset by `distance` from the index `i`. If `distance` is positive, this is the same value as the result of `distance` calls to `index(after:)`. If `distance` is negative, this is the same value as the result of `abs(distance)` calls to `index(before:)`. ## Discussion The following example obtains an index advanced four positions from an array’s starting index and then prints the element at that position. ``` let numbers = [10, 20, 30, 40, 50] let i = numbers.index(numbers.startIndex, offsetBy: 4) print(numbers[i]) // Prints "50" ``` The value passed as `distance` must not offset `i` beyond the bounds of the collection. > Complexity: O(1) --- 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)