# additionalContent(for:) Handles writing non-Core Data content to the additional content directory in the document’s file package. ``` func additionalContent(for absoluteURL: URL) throws -> Any ``` ## Parameters `absoluteURL` The URL for the additional content directory in the document’s file package. ## Return Value An object that contains the additional content for the document at `absoluteURL`, or `nil` if there is a problem. ## Discussion You override this method to perform to manage non-Core Data content to be stored in the additional content directory in the document’s file package. If you implement this method, it’s invoked automatically by [`contents(forType:)`](/documentation/UIKit/UIDocument/contents(forType:)). The returned object is passed to [`writeAdditionalContent(_:to:originalContentsURL:)`](/documentation/UIKit/UIManagedDocument/writeAdditionalContent(_:to:originalContentsURL:)). There’s no need to invoke `super`’s implementation. > Handling Errors in Swift: > In Swift, this method is marked with the `throws` keyword to indicate that it throws an error in cases of failure. > > When overriding this method, use the `throw` statement to throw an `NSError`, as described in [Error Handling](https://docs.swift.org/swift-book/LanguageGuide/ErrorHandling.html) in [The Swift Programming Language](https://docs.swift.org/swift-book/) and `About Imported Cocoa Error Parameters`. ### Special considerations A return value of `nil` indicates an error condition. To avoid generating an exception, you must return a value from this method. If it isn’t always the case that there will be additional content, you should return a sentinel value (for example, an instance) that you check for in [`writeAdditionalContent(_:to:originalContentsURL:)`](/documentation/UIKit/UIManagedDocument/writeAdditionalContent(_:to:originalContentsURL:)). The object returned from this method is passed to [`writeAdditionalContent(_:to:originalContentsURL:)`](/documentation/UIKit/UIManagedDocument/writeAdditionalContent(_:to:originalContentsURL:)). Because [`writeAdditionalContent(_:to:originalContentsURL:)`](/documentation/UIKit/UIManagedDocument/writeAdditionalContent(_:to:originalContentsURL:)) is executed on a different thread, you must ensure that the object you return is thread-safe. For example, you might return an object containing an archive of the state you want to capture. Additional content isn’t supported on iCloud. --- 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)