# assign(to:on:) Assigns each element from a publisher to a property on an object. ``` func assign(to keyPath: ReferenceWritableKeyPath, on object: Root) -> AnyCancellable ``` ## Parameters `keyPath` A key path that indicates the property to assign. See [Key-Path Expression](https://developer.apple.com/library/archive/documentation/Swift/Conceptual/Swift_Programming_Language/Expressions.html#//apple_ref/doc/uid/TP40014097-CH32-ID563) in *The Swift Programming Language* to learn how to use key paths to specify a property of an object. `object` The object that contains the property. The subscriber assigns the object’s property every time it receives a new value. ## Return Value An [`AnyCancellable`](/documentation/Combine/AnyCancellable) instance. Call [`cancel()`](/documentation/Combine/Cancellable/cancel()) on this instance when you no longer want the publisher to automatically assign the property. Deinitializing this instance will also cancel automatic assignment. ## Discussion Use the [`assign(to:on:)`](/documentation/Combine/Publisher/assign(to:on:)) subscriber when you want to set a given property each time a publisher produces a value. In this example, the [`assign(to:on:)`](/documentation/Combine/Publisher/assign(to:on:)) sets the value of the `anInt` property on an instance of `MyClass`: ``` class MyClass { var anInt: Int = 0 { didSet { print("anInt was set to: \(anInt)", terminator: "; ") } } } var myObject = MyClass() let myRange = (0...2) cancellable = myRange.publisher .assign(to: \.anInt, on: myObject) // Prints: "anInt was set to: 0; anInt was set to: 1; anInt was set to: 2" ``` > Important: The ``doc://com.apple.Combine/documentation/Combine/Subscribers/Assign`` instance created by this operator maintains a strong reference to `object`, and sets it to `nil` when the upstream publisher completes (either normally or with an error). --- 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)