# double(forKey:) Returns the double value associated with the specified key. ``` func double(forKey aKey: String) -> Double ``` ## Parameters `aKey` The key to retrieve from the iCloud key-value store. ## Return Value The double value associated with `aKey`, or `0.0` if the key isn’t present. ## Discussion This method automatically coerces certain types to their equivalent double values. The Boolean value `true` becomes `1.0` and `false` becomes `0.0`. An integer becomes the equivalent double –– for example, `2` becomes `2.0`. A string that contains a numerical value contains the equivalent double — for example, “123.4” becomes `123.4`. --- 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)