# NSSecureCoding A protocol that enables encoding and decoding in a manner that is robust against object substitution attacks. ``` protocol NSSecureCoding : NSCoding ``` ## Overview Historically, many classes decoded instances of themselves like this: ```swift if let object = decoder.decodeObjectForKey("myKey") as MyClass { // ...succeeds... } else { // ...fail... } ``` This technique is potentially unsafe because by the time you can verify the class type, the object has already been constructed, and if this is part of a collection class, potentially inserted into an object graph. In order to conform to [`NSSecureCoding`](/documentation/Foundation/NSSecureCoding): - An object that does not override ``doc://com.apple.foundation/documentation/Foundation/NSCoding/init(coder:)`` can conform to `NSSecureCoding` without any changes (assuming that it is a subclass of another class that conforms). - An object that does override ``doc://com.apple.foundation/documentation/Foundation/NSCoding/init(coder:)`` must decode any enclosed objects using the ``doc://com.apple.foundation/documentation/Foundation/NSCoder/decodeObjectOfClass:forKey:`` method. For example: ```swift let obj = decoder.decodeObject(of:MyClass.self, forKey: "myKey") ``` In addition, the class must override the getter for its [`supportsSecureCoding`](/documentation/Foundation/NSSecureCoding/supportsSecureCoding) property to return . For more information about how this relates to the NSXPC API, see [Creating XPC Services](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingXPCServices.html#//apple_ref/doc/uid/10000172i-SW6) in [Daemons and Services Programming Guide](https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/Introduction.html#//apple_ref/doc/uid/10000172i). ## Topics ### Checking for Secure Coding [`supportsSecureCoding`](/documentation/Foundation/NSSecureCoding/supportsSecureCoding) A Boolean value that indicates whether or not the class supports secure coding. --- 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)