Cocoa® Programming

Runtime Functions

The Apple Objective-C runtime provides many C functions for interacting with the runtime. Most of the runtime functions are described in Appendix A. However, four runtime functions are used commonly and deserve explanation here.

Class NSClassFromString(NSString *aClassName) 
NSString *NSStringFromClass(Class aClass) 
NSString *NSStringFromSelector(SEL aSelector) 
SEL NSSelectorFromString(NSString *aSelectorName) 

The first two methods convert from a string to a reference to the class named by the string and back. Uses of NSClassFromString() include allowing a user to input the name of a class to use. For example, an application could parse a text configuration file that specifies which classes to use in the application.

The ...