# compactMapValues(_:) Returns a new dictionary containing only the key-value pairs that have non-`nil` values as the result of transformation by the given closure. ``` func compactMapValues(_ transform: (Value) throws -> T?) rethrows -> Dictionary ``` ## Parameters `transform` A closure that transforms a value. `transform` accepts each value of the dictionary as its parameter and returns an optional transformed value of the same or of a different type. ## Return Value A dictionary containing the keys and non-`nil` transformed values of this dictionary. ## Discussion Use this method to receive a dictionary with non-optional values when your transformation produces optional values. In this example, note the difference in the result of using `mapValues` and `compactMapValues` with a transformation that returns an optional `Int` value. ``` let data = ["a": "1", "b": "three", "c": "///4///"] let m: [String: Int?] = data.mapValues { str in Int(str) } // ["a": Optional(1), "b": nil, "c": nil] let c: [String: Int] = data.compactMapValues { str in Int(str) } // ["a": 1] ``` > Complexity: O(*m* + *n*), where *n* is the length of the original > dictionary and *m* is the length of the resulting dictionary. --- 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)