# init(_:) Creates a new collection difference from a collection of changes. ``` init?(_ changes: Changes) where Changes : Collection, Changes.Element == CollectionDifference.Change ``` ## Parameters `changes` A collection of changes that represent a transition between two states. ## Discussion To find the difference between two collections, use the `difference(from:)` method declared on the `BidirectionalCollection` protocol. The collection of changes passed as `changes` must meet these requirements: - All insertion offsets are unique - All removal offsets are unique - All associations between insertions and removals are symmetric > Complexity: O(*n* * log(*n*)), where *n* is the length of the > parameter. --- 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)