# fetch(with:merge:) Subclasses should override this method to customize a fetch request, for example to specify fetch limits. ``` func fetch(with fetchRequest: NSFetchRequest?, merge: Bool) throws ``` ## Parameters `fetchRequest` The fetch request to use for the fetch. Pass `nil` to use the default fetch request. `merge` If , the receiver merges the existing content with the fetch result, otherwise the receiver replaces the entire content with the fetch result. ## Discussion This method performs a number of actions that you cannot reproduce. To customize this method, you should therefore create your own fetch request and then invoke `super`’s implementation with the new fetch request. > Handling Errors in Swift: > In Swift, this method returns `Void` and is marked with the `throws` keyword to indicate that it throws an error in cases of failure. > > You call this method in a `try` expression and handle any errors in the `catch` clauses of a `do` statement, 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`. --- 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)