Changes

Methods come in two different forms, ''class methods'' and ''instance methods''. Class methods operate at the level of the class, such as creating a new instance of a classand are covered in more detail in [[Writing Objective-C Class Methods]]. Instance methods, on the other hand, operate only on the instance of a class (for example performing an arithmetic operation on two instance variables and returning the result). ''Class methods'' are preceded by a plus (+) sign in the declaration and instance methods are preceded by a minus (-) sign. If the method returns a result, the name of method must be preceded by the data type returned enclosed in parentheses. If a method does not return a result, then the must be declared as ''void''. If data needs to be passed through the member (referred to as ''arguments''), the member name is followed by a colon, the data type in parentheses and a name for the argument. For example, the declaration of a method to set the account number in our example might read as follows: