# WKExtensionDelegateAdaptor A property wrapper type that you use to create a WatchKit extension delegate. ``` @MainActor @preconcurrency @propertyWrapper struct WKExtensionDelegateAdaptor where DelegateType : NSObject, DelegateType : WKExtensionDelegate ``` ## Overview To handle extension delegate callbacks in an extension that uses the SwiftUI life cycle, define a type that conforms to the protocol, and implement the delegate methods that you need. For example, you can implement the method to handle remote notification registration: ``` class MyExtensionDelegate: NSObject, WKExtensionDelegate, ObservableObject { func didRegisterForRemoteNotifications(withDeviceToken: Data) { // Record the device token. } } ``` Then use the `WKExtensionDelegateAdaptor` property wrapper inside your [`App`](/documentation/SwiftUI/App) declaration to tell SwiftUI about the delegate type: ``` @main struct MyApp: App { @WKExtensionDelegateAdaptor private var extensionDelegate: MyExtensionDelegate var body: some Scene { ... } } ``` SwiftUI instantiates the delegate and calls the delegate’s methods in response to life cycle events. Define the delegate adaptor only in your [`App`](/documentation/SwiftUI/App) declaration, and only once for a given extension. If you declare it more than once, SwiftUI generates a runtime error. If your extension delegate conforms to the protocol, as in the example above, then SwiftUI puts the delegate it creates into the [`Environment`](/documentation/SwiftUI/Environment). You can access the delegate from any scene or view in your extension using the [`EnvironmentObject`](/documentation/SwiftUI/EnvironmentObject) property wrapper: ``` @EnvironmentObject private var extensionDelegate: MyExtensionDelegate ``` This enables you to use the dollar sign (`$`) prefix to get a binding to published properties that you declare in the delegate. For more information, see [`projectedValue`](/documentation/SwiftUI/WKExtensionDelegateAdaptor/projectedValue). > Important: Manage an externsion’s life cycle events without using a > delegate whenever possible. For example, prefer to handle changes > in ``doc://com.apple.SwiftUI/documentation/SwiftUI/ScenePhase`` instead of relying on delegate callbacks, like > . ## Topics ### Creating a delegate adaptor [`init(_:)`](/documentation/SwiftUI/WKExtensionDelegateAdaptor/init(_:)) Creates a WatchKit extension delegate adaptor using an observable delegate. ### Getting the delegate adaptor [`projectedValue`](/documentation/SwiftUI/WKExtensionDelegateAdaptor/projectedValue) A projection of the observed object that provides bindings to its properties. [`wrappedValue`](/documentation/SwiftUI/WKExtensionDelegateAdaptor/wrappedValue) The underlying delegate. --- 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)