# read(from:) Reads the document data in a file at a specified location in the application sandbox. ``` func read(from url: URL) throws ``` ## Parameters `url` A file URL that identifies the location of the document file in the application sandbox. This file URL is typically the one returned by the [`fileURL`](/documentation/UIKit/UIDocument/fileURL) property. ## Discussion Typical [`UIDocument`](/documentation/UIKit/UIDocument) subclasses shouldn’t need to call this method directly, especially if the entire file is read at once. The default implementation calls [`load(fromContents:ofType:)`](/documentation/UIKit/UIDocument/load(fromContents:ofType:)) on the queue on which [`open(completionHandler:)`](/documentation/UIKit/UIDocument/open(completionHandler:)) was called to provide the `UIDocument` subclass with the document data object. Subclasses that want more control over the reading of the document file—for example, that want to read a large document file incrementally—can override this method. It isn’t necessary for these subclasses to call the superclass implementation (`super`). > 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`. --- 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)