# init(keyName:searchable:searchableByDefault:unique:multiValued:) Returns a new custom attribute key with the specified name and properties. ``` init?(keyName: String, searchable: Bool, searchableByDefault: Bool, unique: Bool, multiValued: Bool) ``` ## Parameters `keyName` The name of the custom attribute for use as a key in a [`CSSearchableItemAttributeSet`](/documentation/CoreSpotlight/CSSearchableItemAttributeSet). The key name must be a string that contains only ASCII characters and no punctuation other than the underscore (that is, “_”). The prefix `kMD` is reserved. `searchable` A Boolean value that indicates if the attribute can be specified as a search term. `searchableByDefault` A Boolean value that indicates if the attribute should be searchable by default. `unique` A Boolean value that indicates if duplicate values should be treated as the same value to save storage space. `multiValued` A Boolean value that indicates if the attribute is likely to have multiple values, such as arrays, associated with it. ## Return Value A new custom attribute key with the specified name and properties. ## Discussion To create custom attribute key names, it’s recommended that you use a reverse DNS format that includes your company name and does not include the period character (”.”). For example, a key name of the form `com_mycompany_myapp_mykeyname` works well. --- 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)