# keyValueObservingExpectation(for:keyPath:handler:) Creates an expectation that uses Key-Value Observing to observe a value and respond to changes in that value by calling a provided handler. ``` func keyValueObservingExpectation(for objectToObserve: Any, keyPath: String, handler: XCTKVOExpectation.Handler? = nil) -> XCTestExpectation ``` ## Parameters `objectToObserve` The object to observe. `keyPath` The key path to observe. `handler` An optional [`XCTKVOExpectation.Handler`](/documentation/XCTest/XCTKVOExpectation/Handler-swift.typealias) block. If you don’t provide a handler block, the first change to the key path of the observed object fulfills the expectation. ## Discussion Creates an [`XCTestExpectation`](/documentation/XCTest/XCTestExpectation) that uses Key Value Observing to observe changes on the value specified by `keyPath` on the provided object. When the tests detects changes to the value, it calls the `handler` block to assess the new value to see if the change fulfills the expectation. Every key-value observing change runs the handler block until it either returns (to fulfill the expectation), or the wait times out. You can use [`XCTAssert`](/documentation/XCTest/XCTAssert) and related APIs in the block to report a failure. > Note: > For more control over KVO-based expectations, use ``doc://com.apple.xctest/documentation/XCTest/XCTKVOExpectation`` instead of this convenience method. --- 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)