Are you looking for a way to enhance the functionality of existing Objective-C classes without subclassing them? Well, you're in luck because category is here to save the day! Category in Objective-C allows you to add new methods to existing classes, including system classes, without modifying their original implementation. This is incredibly useful when you want to extend the functionality of classes provided by Apple or other third-party libraries. So, how do you use category in Objective-C? Let's dive in. To create a category, start by creating a new file with a .h and .m extension. In the .h file, use the @interface directive, followed by the name of the class you want to extend, and the name of your category. For example: @interface NSString (MyCategory) In the .m file, use the @implementation directive, followed by the name of the class and the category. Then, add the new methods you want to include in your category. For example: @implementation NSString (MyCategory) - (void)myNewMethod { // Your implementation here } @end Now, import the .h file where you want to use the new methods, and you're all set! You can now call myNewMethod on any instance of NSString in your project. Keep in mind that category can't add new instance variables to the class, and if you want to override existing methods, you should use class extensions instead. Category in Objective-C is a powerful feature that can help you keep your code modular, organized, and reusable. By using category, you can extend the functionality of existing classes without altering their original implementation, making your code more flexible and easy to maintain. So, next time you need to add new methods to existing Objective-C classes, remember to reach for the category tool in your programming toolbox. Happy coding!