# class_addMethod(_:_:_:_:) Adds a new method to a class with a given name and implementation. ``` func class_addMethod(_ cls: AnyClass?, _ name: Selector, _ imp: IMP, _ types: UnsafePointer?) -> Bool ``` ## Parameters `cls` The class to which to add a method. `name` A selector that specifies the name of the method being added. `imp` A function which is the implementation of the new method. The function must take at least two arguments—`self` and `_cmd`. `types` An array of characters that describe the types of the arguments to the method. For possible values, see [Objective-C Runtime Programming Guide](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Introduction/Introduction.html#//apple_ref/doc/uid/TP40008048) > [Type Encodings](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/ObjCRuntimeGuide/Articles/ocrtTypeEncodings.html#//apple_ref/doc/uid/TP40008048-CH100). Since the function must take at least two arguments—`self` and `_cmd`, the second and third characters must be “`@:`” (the first character is the return type). ## Return Value [`YES`](/documentation/ObjectiveC/YES) if the method was added successfully, otherwise [`NO`](/documentation/ObjectiveC/NO) (for example, the class already contains a method implementation with that name). ## Discussion [`class_addMethod(_:_:_:_:)`](/documentation/ObjectiveC/class_addMethod(_:_:_:_:)) will add an override of a superclass’s implementation, but will not replace an existing implementation in this class. To change an existing implementation, use [`method_setImplementation(_:_:)`](/documentation/ObjectiveC/method_setImplementation(_:_:)). An Objective-C method is simply a C function that take at least two arguments—`self` and `_cmd`. For example, given the following function: ```objc void myMethodIMP(id self, SEL _cmd) { // implementation .... } ``` you can dynamically add it to a class as a method (called `resolveThisMethodDynamically`) like this: ```objc class_addMethod([self class], @selector(resolveThisMethodDynamically), (IMP) myMethodIMP, "v@:"); ``` --- 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)