# joined(separator:) Returns the concatenated elements of this sequence of sequences, inserting the given separator between each element. ``` func joined(separator: Separator) -> JoinedSequence where Separator : Sequence, Separator.Element == Self.Element.Element ``` ## Parameters `separator` A sequence to insert between each of this sequence’s elements. ## Return Value The joined sequence of elements. ## Discussion This example shows how an array of `[Int]` instances can be joined, using another `[Int]` instance as the separator: ``` let nestedNumbers = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] let joined = nestedNumbers.joined(separator: [-1, -2]) print(Array(joined)) // Prints "[1, 2, 3, -1, -2, 4, 5, 6, -1, -2, 7, 8, 9]" ``` --- 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)