# objc_allocateClassPair(_:_:_:) Creates a new class and metaclass. ``` func objc_allocateClassPair(_ superclass: AnyClass?, _ name: UnsafePointer, _ extraBytes: Int) -> AnyClass? ``` ## Parameters `superclass` The class to use as the new class’s superclass, or `Nil` to create a new root class. `name` The string to use as the new class’s name. The string will be copied. `extraBytes` The number of bytes to allocate for indexed ivars at the end of the class and metaclass objects. This should usually be `0`. ## Return Value The new class, or `Nil` if the class could not be created (for example, the desired name is already in use). ## Discussion You can get a pointer to the new metaclass by calling `object_getClass(newClass)`. To create a new class, start by calling [`objc_allocateClassPair(_:_:_:)`](/documentation/ObjectiveC/objc_allocateClassPair(_:_:_:)). Then set the class’s attributes with functions like [`class_addMethod(_:_:_:_:)`](/documentation/ObjectiveC/class_addMethod(_:_:_:_:)) and [`class_addIvar(_:_:_:_:_:)`](/documentation/ObjectiveC/class_addIvar(_:_:_:_:_:)). When you are done building the class, call [`objc_registerClassPair(_:)`](/documentation/ObjectiveC/objc_registerClassPair(_:)). The new class is now ready for use. Instance methods and instance variables should be added to the class itself. Class methods should be added to the metaclass. --- 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)