# enumerate(_:batchSize:allowEscapingMutations:block:) Runs a closure for each model that matches the criteria of the specified fetch descriptor. ``` func enumerate(_ fetch: FetchDescriptor, batchSize: Int = 5000, allowEscapingMutations: Bool = false, block: (T) throws -> Void) throws where T : PersistentModel ``` ## Parameters `fetch` A fetch descriptor that provides the configuration for the fetch. `batchSize` The maximum number of models to include in each batch. The default value is 5000. `allowEscapingMutations` A Boolean value that determines whether the closure can leave the context in a modified state after it completes. The default value is `false`. `block` The closure to run for each fetched model. --- 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)