# init(properties:id:uniquingKeysWith:) Creates generated content from key-value pairs, resolving duplicate keys with a combining closure. ``` init(properties: S, id: GenerationID? = nil, uniquingKeysWith combine: (GeneratedContent, GeneratedContent) throws -> some ConvertibleToGeneratedContent) rethrows where S : Sequence, S.Element == (String, any ConvertibleToGeneratedContent) ``` ## Parameters `properties` A sequence of key-value pairs to use for the new content. `id` A unique id associated with [`GeneratedContent`](/documentation/FoundationModels/GeneratedContent). `combine` A closure that is called with the values to resolve any duplicates keys that are encountered. The closure returns the desired value for the final content. ## Discussion The order of properties is important. For [`Generable`](/documentation/FoundationModels/Generable) types, the order must match the order properties in the types `schema`. You use this initializer to create generated content when you have a sequence of key-value tuples that might have duplicate keys. As the content is built, the initializer calls the `combine` closure with the current and new values for any duplicate keys. Pass a closure as `combine` that returns the value to use in the resulting content: The closure can choose between the two values, combine them to produce a new value, or even throw an error. The following example shows how to choose the first and last values for any duplicate keys: ```swift let content = GeneratedContent( properties: [("name", "John"), ("name", "Jane"), ("married", true)], uniquingKeysWith: { (first, _) in first } ) // GeneratedContent(["name": "John", "married": true]) ``` --- 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)