# filter(_:) Returns an array containing, in order, the elements of the sequence that satisfy the given predicate. ``` func filter(_ isIncluded: (Self.Element) throws(E) -> Bool) throws(E) -> [Self.Element] where E : Error ``` ## Parameters `isIncluded` A closure that takes an element of the sequence as its argument and returns a Boolean value indicating whether the element should be included in the returned array. ## Return Value An array of the elements that `isIncluded` allowed. ## Discussion In this example, `filter(_:)` is used to include only names shorter than five characters. ``` let cast = ["Vivien", "Marlon", "Kim", "Karl"] let shortNames = cast.filter { $0.count < 5 } print(shortNames) // Prints "["Kim", "Karl"]" ``` > Complexity: O(*n*), where *n* is the length of the sequence. --- 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)