# NSLock An object that coordinates the operation of multiple threads of execution within the same application. ``` class NSLock ``` ## Overview An [`NSLock`](/documentation/Foundation/NSLock) object can be used to mediate access to an application’s global data or to protect a critical section of code, allowing it to run atomically. > Warning: > The ``doc://com.apple.foundation/documentation/Foundation/NSLock`` class uses POSIX threads to implement its locking behavior. When sending an unlock message to an ``doc://com.apple.foundation/documentation/Foundation/NSLock`` object, you must be sure that message is sent from the same thread that sent the initial lock message. Unlocking a lock from a different thread can result in undefined behavior. You should not use this class to implement a recursive lock. Calling the `lock` method twice on the same thread will lock up your thread permanently. Use the [`NSRecursiveLock`](/documentation/Foundation/NSRecursiveLock) class to implement recursive locks instead. Unlocking a lock that is not locked is considered a programmer error and should be fixed in your code. The [`NSLock`](/documentation/Foundation/NSLock) class reports such errors by printing an error message to the console when they occur. ## Topics ### Acquiring a Lock [`lock(before:)`](/documentation/Foundation/NSLock/lock(before:)) Attempts to acquire a lock before a given time and returns a Boolean value indicating whether the attempt was successful. [`try()`](/documentation/Foundation/NSLock/try()) Attempts to acquire a lock and immediately returns a Boolean value that indicates whether the attempt was successful. ### Naming the Lock [`name`](/documentation/Foundation/NSLock/name) The name associated with the receiver. --- 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)