Registers a method name with the Objective-C runtime system.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
A pointer to a C string. Pass the name of the method you wish to register.
A pointer of type
SEL specifying the selector for the named method.
The implementation of this method is identical to the implementation of
Prior to OS X version 10.0, this method tried to find the selector mapped to the given name and returned
NULL if the selector was not found. This was changed for safety, because it was observed that many of the callers of this function did not check the return value for