# automaticallyNotifiesObservers(forKey:) Returns a Boolean value that indicates whether the observed object supports automatic key-value observation for the given key. ``` class func automaticallyNotifiesObservers(forKey key: String) -> Bool ``` ## Return Value [`YES`](/documentation/ObjectiveC/YES) if the key-value observing machinery should automatically invoke [`willChangeValue(forKey:)`](/documentation/ObjectiveC/NSObject-swift.class/willChangeValue(forKey:))/[`didChangeValue(forKey:)`](/documentation/ObjectiveC/NSObject-swift.class/didChangeValue(forKey:)) and [`willChange(_:valuesAt:forKey:)`](/documentation/ObjectiveC/NSObject-swift.class/willChange(_:valuesAt:forKey:))/[`didChange(_:valuesAt:forKey:)`](/documentation/ObjectiveC/NSObject-swift.class/didChange(_:valuesAt:forKey:)) whenever instances of the class receive key-value coding messages for the `key`, or mutating key-value-coding-compliant methods for the `key` are invoked; otherwise [`NO`](/documentation/ObjectiveC/NO). ## Discussion The default implementation returns [`YES`](/documentation/ObjectiveC/YES). Starting in OS X 10.5, the default implementation of this method searches the receiving class for a method whose name matches the pattern `+automaticallyNotifiesObserversOf`, and returns the result of invoking that method if it is found. Any found methods must return `BOOL`. If no such method is found [`YES`](/documentation/ObjectiveC/YES) is returned. --- 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)