# NSLocking The elementary methods adopted by classes that define lock objects. ``` protocol NSLocking ``` ## Overview A lock object is used to coordinate the actions of multiple threads of execution within a single application. By using a lock object, an application can protect critical sections of code from being executed simultaneously by separate threads, thus protecting shared data and other shared resources from corruption. ## Topics ### Working with Locks [`lock()`](/documentation/Foundation/NSLocking/lock()) Attempts to acquire a lock, blocking a thread’s execution until the lock can be acquired. [`unlock()`](/documentation/Foundation/NSLocking/unlock()) Relinquishes a previously acquired lock. --- 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)