Defining and Declaring a Function

A function definition in Objective-C consists of two parts: a function header and a function body. The function header specifies the name, return type, and parameters of the function. The function body contains a collection of statements that define what the function does.

Syntax:

return_type function_name(parameter_list)

{

// body of the function

}

Example:

Below code defines a function called max that takes two integers as parameters and returns the maximum between them:

int max(int num1, int num2)

{

int result;

if (num1 > num2)

{

result = num1;

}

else

{

result = num2;

}

return result;

}

A function declaration tells the compiler about the name, return type, and parameters of a function. The actual body of the function can be defined separately. A function declaration has the same syntax as the function header, followed by a semicolon.

For example, the following code declares the max function:

int max(int num1, int num2);

A function declaration is also known as a function prototype. It is usually placed at the beginning of a source file or in a header file. A function declaration is optional, but it is recommended to declare a function before using it to avoid compiler errors or warnings.

Objective-C is a general-purpose, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. It is the main programming language used by Apple for the OS X and iOS operating systems and their respective application programming interfaces (APIs), Cocoa and Cocoa Touch.

One of the features of Objective-C is that it supports functions, which are named blocks of code that can be called upon to perform a specific task. Functions can be provided with data on which to perform the task and can return a result to the code that called them. Functions can help to organize the code, avoid repetition, and improve readability and maintainability.