Custom views Do custom drawing. Mouse events Make your custom view deal with mouse events, images, and the open panel. Keyboard events Make your custom view deal with keyboard events. Fonts Attributed strings Draw character strings in your custom view. Pasteboard Responder chain Implement copy, cut, and paste.
Categories Add a method to an existing class.
Drag and Drop Add drag and drop to your custom views. Timers Create and use timers. Sheets Attach sheets to your window. Formatters Format a character string and convert it to another type with a custom formatter subclass. Printing Add printing to your application.