Suman's courses

“Method”, “message”, and “function” all (sort of) refer to the same thing in Objective-C.

A method is a section of code that we can call from elsewhere in our code.

Components to methods:

1. Declaration
2. Definition
3. Invocation

Declaration- the act of informing other objects about a function's name, return type, and parameters.

Declarations for public methods are included in the header files of Objective-C objects.

Declarations for private methods are included in the Definition and do not need additional code. These methods can only be called within a class.

Declarations take the form:

• - (RETURNTYPE) METHODNAME:(ARGUMENTTYPE*)ARGUEMENTNAME METHODNAME2:(ARGUMENTTYPE*)ARGUEMENTNAME2;

A dash at the start indicates a instance method. Can only be called on an instantiated object. When creating a method, always use a dash unless you have some overriding reason.

A plus sign at the start indicates a class method. Can only be called on the class itself, commonly used as custom initialization method.

Definition- writing the code that executes/is contained within the method. Known as the method body.

Defining a Method Return Type: A method may return a value. The return_type is the data type of the value the function returns. Some methods perform the desired operations without returning a value. In this case, the return_type is the keyword void.

Method Name: This is the actual name of the method. The method name and the parameter list together constitute the method signature.

Arguments: A argument is like a placeholder. When a function is invoked, you pass a value to the argument. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the arguments of a method. Arguments are optional; that is, a method may contain no argument.

Joining Argument: A joining argument is to make it easier to read and to make it clear while calling it.

Method Body: The method body contains a collection of statements that define what the method does.

Declaration Method declaration is required when you define a method in one source file and you call that method in another file. In such case you should declare the function at the top of the file calling the function.