Introduction to Objective-C

Refer to the first part of the tutorial from this link: http://iosmadesimple.blogspot.com/2012/07/introduction-to-xcode.html

Objectives:

• To understand the class structure and its implementation in Objective-C
• To get acquainted with Objective-C syntax

Objective-C uses Model-View-Controller design pattern. If you want to know more about MVC design pattern in Objective-C, refer to this link from Cocoa Lab. http://www.cocoalab.com/?q=node/24

Class Structure

1. Interface Section - where your data components and function headers are located; found in .h files
2. Implementation Section - where your implementation for your functions are located; found in .m files
3. Program Section - these are your codes; where your instatiate objects to carry out your tasks

Class Definition and Instatiation Syntax

Interface (.h files)

@interface NameOfClass:ParentClass {

//instance variables

returnType nameOfVariable;

}

//instance methods

- (returnType)methodName1; //No Parameters

- (returnType)methodName2:(returnType)parameter; //With One Parameter

- (returnType)methodName3:(returnType)parameter1 ThisIsPartOfTheMethodNameWithData:(returnType)parameter2; //With MultipleParameters

@end

Implementation (.m files)

@implementation NameOfClass

- (returnType)methodName1 {

//Put your codes here

}

- (returnType)methodName2:(returnType)parameter {

//Put your codes here

}

- (returnType)methodName3:(returnType)parameter1 ThisIsPartOfTheMethodNameWithData:(returnType)parameter2 {

//Put your codes here

}

@end

Program

main.m file //Remeber to import the class you created

int main(int argc, char *argv[]) {

//Create instance of the class

NameOfClass *instanceName1 = [[NameOfClass alloc] init];

//Or you may do it this way

NameOfClass *instanceName2;

instanceName2 = [NameOfClass alloc];

instanceName2 = [NameOfClass init];

//Calling a class function

[instanceName2 methodName];

[instanceName2 methodName2:100]; //assume that the dataType of the parameter is int, let's pass integer 100

//If you no longer need the objects, release their memory

[instanceName1 release];

[instanceName2 release];

}