Object Oriented Programming using Objective-C

• Methods are invoked by sending messages to the object
• Messages will only ask to perform an activity, not the data that it’ll be performed on. Object decides what data it’ll be performed on
• An object can be redefined as receiver to conduct the same activity on a different set of data or a different activity altogether. Receiver is sort of an instance of an object.
• The result of a message can’t be calculated from the message or method name alone; it also depends
  on the object that receives the message
• Using the static storage class designator to limit the scope of names to just the files
  where they’re declared enhances the independence of source modules
• Function names are global; each function must have a unique name (except for those declared static).
• A function is useful only to those who agree to use the same kind of data structures it accepts as arguments. Because it hides its data, an object doesn’t have this problem. This is one of the principal reasons why classes can be reused more easily than functions.
• Must use, Implementation and Interfaces seperately to hide information.